SUPREME COURT OF VICTORIA
COURT OF APPEAL	
	
S EAPCR 2025 0052

DIRECTOR OF PUBLIC PROSECUTIONS	Applicant	
		
v		
		
ERIN PATTERSON	Respondent	

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JUDGES:	EMERTON P, PRIEST and T FORREST JJA	
WHERE HELD:	Melbourne	
DATE OF HEARING:	3 April 2025	
DATE OF JUDGMENT:	17 April 2025	
MEDIUM NEUTRAL CITATION:	[2025] VSCA 82	
JUDGMENT APPEALED FROM:	R v Patterson (Ruling 6) [2025] VSC 108R (Beale J)	

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CRIMINAL LAW – Interlocutory appeal – Coincidence evidence – Three charges of murder and one of attempted murder by alleged poisoning of four lunch guests – Three charges of attempted murder of husband by alleged poisoning in three preceding episodes – Whether evidence relating to alleged poisoning of lunch guests admissible to prove that husband was poisoned – Whether evidence relating to alleged poisoning of husband admissible to prove lunch guests deliberately poisoned – Whether circular reasoning – Whether charges relating to husband should be severed from those relating to lunch guests – Whether probative value of coincidence evidence substantially outweighs any prejudicial effect on the accused – Judge was correct to sever indictment – Leave to appeal refused.
Evidence Act 2008 ss 98(1), 101(2); Perry v The Queen (1982) 150 CLR 580 considered.
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Counsel	
Appellant		Dr N Rogers SC with Ms S Lenthall	
Respondent 		Mr C Mandy SC with Ms S Stafford	
	
Solicitors	
Appellant		Ms A Hogan, Solicitor for Public Prosecutions	
Respondent		Doogue + George	

EMERTON P
T FORREST JA:
Introduction
1	The respondent is charged with four counts of attempted murder (charges 1–4) and three counts of murder (charges 5–7). Charges 1, 2 and 3 relate to three separate incidents involving the respondent’s estranged husband, Simon Patterson (Events 1, 2 and 3 respectively). Charges 4, 5, 6 and 7 relate to one incident (Event 4) involving four members of Simon Patterson’s family — Gail and Donald Patterson (Simon’s parents) and Heather and Ian Wilkinson (Simon’s maternal aunt and her husband).
2	The prosecution alleges that the respondent deliberately poisoned the five family members with meals she prepared that contained either an unknown poison or poisons (charges 1–3) or death cap mushrooms (charges 4–7).
3	On 24 January 2024, the prosecution filed a notice of its intention to adduce coincidence evidence to establish that the respondent deliberately poisoned the family members or intended to do so.
4	Section 98(1) of the Evidence Act 2008 governs the use of coincidence evidence and relevantly provides:
	Evidence that 2 or more events occurred is not admissible to prove that a person did a particular act or had a particular state of mind on the basis that, having regard to any similarities in the events or the circumstances in which they occurred, or any similarities in both the events and the circumstances in which they occurred, it is improbable that the events occurred coincidentally unless—
	…
(b) the court thinks that the evidence will, either by itself or having regard to other evidence adduced or to be adduced by the party seeking to adduce the evidence, have significant probative value.
5	Section 101(2) of the Evidence Act imposes an additional constraint on the use of coincidence evidence in criminal trials:
	… coincidence evidence about an accused, that is adduced by the prosecution, cannot be used against the accused unless the probative value of the evidence substantially outweighs any prejudicial effect it may have on the accused.
6	The facts that the prosecution seeks to prove (at least in part) by relying on the improbability of coincidence are:
(a)	the illnesses suffered by the persons affected were caused by consuming food prepared by the respondent;
(b)	the food prepared by the respondent was poisoned; and
(c)	the respondent deliberately poisoned the food.
7	The points of similarity relied on by the prosecution are:
S.1: 	the respondent was related by marriage to each victim;
S.2: 	the respondent initiated/instigated each activity with Simon, and the four lunch guests, and arranged to provide/serve food; 
S.3: 	the respondent prepared the food;
S.4: 	the respondent allocated the food;
S.5: 	the respondent ate separate meals from Simon and from the four lunch guests;
S.6: 	the respondent’s two children were not present when the food was served to Simon and the four lunch guests;
S.7: 	after consuming the food, Simon and the four lunch guests suffered from severe gastrointestinal illnesses; and
S.8: 	at a time before or shortly after each event, the respondent used a computer or other electronic device to access online content relating to poisons. 
8	The prosecution submits that having regard to the similarities in these events and/or circumstances in which they occurred, ‘it is improbable that each of the alleged victims suffered severe gastrointestinal illnesses after having consumed food prepared for them by the [respondent] coincidentally’. 
9	On 14 March 2025, the trial judge ruled that the probative value of the coincidence evidence was substantially outweighed by the significant danger or risk of unfair prejudice to the respondent. The evidence could not be used for coincidence reasoning and charges 1 to 3 should be severed from the indictment.
10	The prosecution seeks leave to appeal the Ruling on the following grounds:
	Ground 1: The trial judge erred in finding that the coincidence evidence invites circular reasoning, and is therefore inadmissible on the basis of Perry v R (1982) 150 CLR 580.
	Ground 2: The trial judge erred in failing to properly assess the similarities between Events 1 to 4, and therefore failed to properly assess the probative value of the coincidence evidence.
	Ground 3: The trial judge erred in failing to properly assess the prejudicial effect that the coincidence evidence may have on the respondent.
Summary of Prosecution Opening 
11	The respondent and Simon married in June 2007 and had two children together. In 2015, they separated, but continued to communicate with one another, and with other members of the Patterson family.
12	Between 2021 and 2022, Simon suffered multiple episodes of serious illness, each of which resulted in hospitalisation following the onset of gastrointestinal illness. These illnesses are the subject of charges 1, 2 and 3.
Charge 1 – 16 November 2021 – Trip to Wilsons Promontory
13	In 2019, the respondent suggested that she and Simon go away to South Africa together without their children. They were scheduled to leave in March or April 2020, but the trip was cancelled due to the onset of the COVID-19 pandemic. The respondent suggested that they go on a hiking and camping trip to Wilsons Promontory instead. This eventually took place in November 2021.
14	On Tuesday 16 November 2021, the respondent went to Simon’s house to pack for the hiking trip. She gave him a Tupperware container of penne Bolognese that she said she had made for the children. After the respondent left, Simon ate the pasta before going to bed. The next morning, he felt unwell. He drove to the respondent’s house to pick her up for the trip and vomited a number of times shortly after arriving at the house. He attributed his condition to stress.
15	Simon continued to vomit as they were driving to Wilsons Promontory. They stopped at Meeniyan for Simon to use the public toilets as he was suffering from diarrhoea. The respondent booked an Airbnb near Wilsons Promontory where the pair stayed for two nights. Simon continued to vomit and suffer from diarrhoea. He suggested they go to the hospital, but the respondent told him that that might involve a long wait. She gave him electrolyte fluids and water.
16	On Friday 19 November 2021, the respondent eventually took Simon to the Urgent Care Centre at Leongatha Hospital, where he was diagnosed with severe dehydration due to gastroenteritis. A blood test showed that he was suffering from acute renal impairment (kidney injury) with elevated creatinine levels and modestly elevated lactate. He was treated with intravenous fluids and was discharged the following morning. He returned to hospital on 21 November 2021 as advised, and was transferred to Monash Medical Centre, where he remained until 27 November 2021.
17	While Simon was in hospital, medical staff undertook extensive testing to investigate the cause of his acute renal failure. They were unable to determine the underlying cause of his illness.
Charge 2 – 25 May 2022 – Trip to Howqua
18	Sometime after the November 2021 trip, the respondent suggested to Simon that they go camping again, as they had missed out on the trip to Wilsons Promontory. Simon agreed and they planned a trip to Howqua, again without their children.
19	About a week before the scheduled trip, Simon went to the respondent’s house one evening. The respondent was making chicken korma curry and wanted Simon and the children to taste test the various levels of spice in the curry. Simon tasted the curries and selected his preferred one.
20	On 24 May 2022, Simon and the respondent went camping near Howqua and stayed at a public campground. On the second evening, they ate chicken korma curry with rice that the respondent had brought pre-prepared. Simon did not see how the meal was packaged or prepared. The next morning, Simon began to feel unwell. He vomited and had diarrhoea throughout the morning. The respondent drove him to Mansfield Hospital, stopping along the way so that he could vomit.
21	Simon was treated with intravenous fluids and discharged later that day after he had stopped vomiting. The pair stayed in an Airbnb in Mansfield. The next morning, they drove home. Simon was still feeling unwell, but he stayed the night alone at his house.
22	On 29 May 2022, Simon was still feeling unwell and called the respondent for help. She went to Simon’s house and called an ambulance. He was taken to Monash Casey Hospital and was admitted in haemodynamic shock. Initial blood testing revealed severe lactic metabolic acidosis, hypothermia, multi-organ failure, marked elevation of ALT suggesting liver ischemia and a blood film consistent with severe sepsis. He was admitted to the intensive care unit and intubated.
23	Simon underwent various investigative procedures while in hospital, but doctors were unable to determine the cause of his illness. He was extubated on 14 June 2022 and on 22 June he was transferred to a rehabilitation centre, where he remained until 8 July 2022. Following his discharge from the rehabilitation centre, he stayed with the respondent for a few weeks. During this time, he tended to prepare his own food.
24	On 14 July 2022, Simon’s General Practitioner, Dr Ford, referred him to a gastroenterologist, Associate Professor Christopher Mills. Simon was required to undergo weekly blood tests for a month followed by fortnightly blood tests to see if the cause of his illness could be determined.
25	On 22 July 2022, the respondent prepared beef stew with rice which both she and Simon ate for lunch. The next morning, Simon became ill again, vomiting and experiencing diarrhoea. He attended Leongatha Hospital and was transferred to Monash Medical Centre, where he remained for a few days. An abdominal CT scan was performed which showed a collection in the left upper quadrant with the anterior aspect touching the transverse colon. He was discharged on 25 July 2022 and returned to the respondent’s home. Shortly after returning, the respondent told Simon that she resented him and regretted asking him to stay with her. Later that day, Simon returned to his own home.
26	On 25 August 2022, Simon consulted with Associate Professor Mills, who noted that Simon’s history was highly unusual and that he had never seen a case like it before.
Charge 3 – 6 September 2022 – Trip to Wilsons Promontory
27	In late August or early September 2022, Simon and the respondent spoke on the phone. The respondent suggested that the pair catch up in person. Simon suggested that they go for a walk at Wilsons Promontory one day when the children were at school. The respondent offered to bring lunch.
28	On the morning of 6 September 2022, Simon did a routine stool sample for Associate Professor Mills. Later that day, he and the respondent went for a walk at Wilsons Promontory. The respondent brought them each a separate, pre-prepared lunch: Simon had a chicken curry wrap wrapped in aluminium foil; the respondent ate what appeared to be the same curry filling except on a plate without the wrap.
29	Shortly after eating lunch, Simon began to feel unwell. He started to vomit and experience diarrhoea. The respondent drove him to Donald and Gail Patterson’s house and they called an ambulance. In the ambulance, Simon suffered a seizure and was in a reduced conscious state. He was admitted to Monash Casey Hospital intensive care unit and was intubated. He remained in hospital for three days and was discharged on 9 September 2022.
30	The routine stool sample from the morning of 6 September was unremarkable.
Charges 4–7 – 29 July 2023
31	On 16 July 2023, the respondent spoke to Simon at the conclusion of a church service they both attended. She invited Simon to have lunch with her on 29 July together with Donald, Gail, Heather and Ian, whom she said she had already invited. The respondent said that the purpose of the lunch was to discuss some medical issues that she had. Simon suggested a morning tea instead, to which the respondent replied, ‘I want it to be lunch’.
32	Dr Ford was also present at the church service that day and recalls the respondent asking Simon to lunch and Simon telling him afterwards that he would politely decline the invitation.
33	On 28 July 2023, Simon sent the respondent a text message saying that he would not be attending the lunch. The respondent replied that she was disappointed as she had spent many hours preparing the lunch and she hoped he would change his mind. Simon informed his parents that he would not be attending.
34	On the morning of 29 July 2023, the respondent told her children that they were to go to McDonalds with a friend, [redacted], for lunch and then to the cinema, as she had organised a lunch for the adults. She drove them to McDonalds at around 12 pm.
35	The four lunch guests arrived at the respondent’s house at around 12:30 pm.
36	Gail and Heather offered to help the respondent in the kitchen but she told them that she had it all in hand.
37	The respondent plated the meals, which consisted of individual beef wellingtons, mashed potato and green beans. The beef wellingtons were prepared as a piece of steak covered with mushrooms and completely encased in pastry. There were four large grey coloured dinner plates and one smaller plate which was lighter in colour. Once the food had been plated by the respondent, Heather and Gail moved the four large plates from the bench to the table and the respondent took the smaller lighter coloured plate to her place at the table. Donald, Gail, Ian and Heather each ate from a large grey coloured dinner plate. The respondent ate from the smaller, lighter coloured plate.
38	Ian and Heather ate their entire portion. Gail ate approximately half of her serve and gave the rest to Donald, who ate his own as well as some of Gail’s. The respondent also ate a beef wellington. After the main meal, they ate dessert, which consisted of a cake brought by Gail and a fruit platter prepared by Heather.
39	After they had finished eating, the respondent announced that she had cancer and asked for advice on whether or not to tell the children.
40	At approximately 2:25 pm, Simon picked up the children from the cinema. He dropped [redacted] and [redacted] at the respondent’s house at 2:30 pm. After some conversation, the lunch guests all left around 3 pm.
41	Approximately eleven to twelve hours after the lunch, each lunch guest developed severe gastroenteritis-like symptoms, including nausea, vomiting and diarrhoea.
42	Donald and Gail called an ambulance sometime around dawn the next morning. The ambulance arrived at 9:15 am and they were transported to Korumburra Hospital. Donald had rung Simon at around 8:45 am that morning and told him that he and Gail were vomiting and had diarrhoea and that they had called an ambulance. Heather had called Donald and Gail earlier that morning and told them that she and Ian were sick. Donald passed this information onto Simon, who went to Ian and Heather’s house and drove them to Leongatha Hospital.
43	Simon rang Dr Ford and told him about Donald and Gail. Dr Ford was familiar with Simon’s previous illnesses and aware of his concerns about potential poisoning. He made contact with the hospital to notify them of his concerns regarding potential poisoning. All four lunch guests were eventually transferred to Dandenong Hospital.
44	On 31 July 2023, two days after the lunch, the respondent presented herself to Leongatha Hospital with diarrhoea after Simon had suggested that she do so. When told by hospital staff that she would need to be transferred to Dandenong Hospital as she had eaten the same food as the four lunch guests, she was reluctant and said she wanted to go home as she had not prepared to spend the night. She eventually signed a discharge against medical advice form, but said that she would return in 20 minutes. One of the doctors at the hospital called police as he was concerned for her safety. The respondent returned to hospital soon after. When police arrived at her house, she had already returned to hospital. The police retrieved the leftover beef wellington from the rubbish bin and delivered it to the hospital. Hospital staff urged the respondent to call her children’s school as they had eaten some of the leftover meat (with the mushrooms scraped off) but the respondent was once again reluctant to do so as she did not want to scare them.
45	The next day, the respondent appeared clinically well and was discharged from hospital.
46	Heather passed away on 4 August 2023 from altered liver function and multiple organ failure with a clinical diagnosis of amanita mushroom poisoning.
47	Gail also passed away on 4 August 2023 with multiple organ failure resulting from altered liver function due to clinically diagnosed amanita mushroom poisoning.
48	Donald passed away on 5 August 2023 from refractory multiple organ failure secondary to altered liver function due to clinically diagnosed amanita mushroom poisoning.
49	Ian’s condition gradually improved and he was extubated on 14 August 2023. He was discharged to a rehabilitation ward on 11 September 2023.
50	The respondent’s medical files from 30 July 2023 were examined by an intensive care specialist who found no abnormal test results, save for slightly elevated fibrinogen.
51	It is the prosecution case that the respondent did not ingest death cap mushrooms at the lunch and did not suffer from amanita poisoning.
The trial judge’s ruling
52	At the outset, the trial judge excluded similarity 8 and similarity 6 from his consideration of the evidence. In relation to similarity 8, this was because there were only two admissible instances of the respondent allegedly accessing information about poisons online. In relation to similarity 6, his Honour considered the evidence to be inconsequential, stating that it was commonplace for adults to go on outings together and host lunches without children being present.
53	The judge relied on the High Court decision in Perry v R, which concerned the admissibility of similar fact evidence and the problem of circular reasoning.
54	In Perry, there was no dispute that the victim had suffered arsenic poisoning. The question was whether he had suffered accidental poisoning or had been deliberately poisoned by the accused, his wife. The similar facts relied on were that the accused’s second husband and brother had died from arsenic poisoning and her de facto husband had, some time before his death from an overdose of sleeping tablets, exhibited symptoms consistent with arsenic poisoning.
55	The trial judge summarised the High Court’s decision as follows:
	The Court was unanimous that the evidence in relation to Mr Duncan [de facto husband] should not have been admitted as part of the similar fact evidence. Gibbs CJ, Murphy and Brennan JJ all considered that the evidence regarding Mr Duncan invited circular reasoning. Gibbs CJ at pp589–590 said ‘[i]t was necessary for the Crown to rely on the other instances of poisoning, including those the subject of the present charges, in an attempt to provide a basis for an inference that Duncan had suffered from arsenical poisoning. In other words, it was necessary to assume the guilt of the applicant of the offences of which she was charged in order to render admissible the evidence regarding the death of Duncan’. Murphy J said at p595 that ‘… on the prosecution’s theory, the supposed poisoning of Duncan depended on acceptance that Haag [second husband], Montgomerie [brother] and Perry were poisoned by the applicant, but the proof of these poisonings depended on the acceptance that she poisoned Duncan’. Brennan J said at p612 that ‘the suspicion that [Duncan’s] symptoms were caused by arsenical poisoning arises in part — as the Crown conceded — from the fact that Mr Perry suffered from chronic arsenical poisoning. But the mere ingestion of arsenic by Mr Perry could throw no light upon the cause of Duncan’s symptoms unless it be assumed that the arsenic ingested by Mr Perry had been administered to him by Mrs Perry [the accused]’.
56	The trial judge turned to consider whether there was circular reasoning of that kind in the present case:
	Does the prosecution’s coincidence evidence in the present case also invite circular reasoning? It is not in dispute that the accused prepared and provided poisoned meals to her lunch guests. What is in dispute is whether she did so deliberately. Is it necessary to first find that the accused deliberately provided poisoned meals to her lunch guests before one could find that the accused provided poisoned meals to Simon Patterson? The answer in my view is ‘Yes’ and, as such, the coincidence evidence does not have significant probative value.
57	Having concluded that the coincidence evidence sought to be relied upon invited a form of impermissible circular reasoning, the trial judge found that even if the coincidence evidence had significant probative value, it failed to clear the additional hurdle that is created by s 101 of the Evidence Act. His Honour considered that a finding that the respondent deliberately poisoned the four lunch guests would create a very significant risk of the jurors misusing or overvaluing the evidence in relation to the charges concerning Events 1 to 3.
58	The judge concluded:
	Would the jurors in the present case be as rigorous in applying the criminal standard of proof as they should be, if they formed the view that the accused had deliberately and fatally poisoned Simon Patterson’s mother, father and aunt and had deliberately and nearly fatally poisoned his uncle? Would the jurors be able to dispassionately assess the evidence specific to Charges 1–3 and pay full heed to the limitations of the medical evidence regarding the possible causes of Simon Patterson’s severe illnesses. Moreover, would the jurors be able to resist rank propensity reasoning such as ‘[s]he deliberately poisoned Simon Patterson’s parents, uncle and aunty: isn’t it likely, then, that she deliberately poisoned Simon Patterson?’ All of these dangers or risks could, of course, be the subject of directions, but the guiding principle that jurors can generally be trusted to abide by directions admits of exceptions. Even if the impugned evidence is credited with significant probative value, I am not persuaded that its probative value substantially outweighs the significant danger or risk of unfair prejudice to the accused.
59	The parties had agreed that if the coincidence evidence were to be ruled inadmissible there would need to be two trials. His Honour made an order pursuant to s 193 of the Criminal Procedure Act 2009 that the indictment be severed.
Ground 1: Circular reasoning?
60	Ground 1 is that the trial judge erred in finding that the coincidence evidence invites circular reasoning and is therefore inadmissible on the basis of Perry.
Prosecution submissions
61	The prosecution argues that the High Court’s reasoning in Perry is inapplicable in this case, having regard to what needs to be proved to establish the similarities. Contrary to the holding of the trial judge, Perry is not on all fours with the present case.
62	The prosecution submits that, unlike in Perry, each similarity on which it seeks to rely is capable of independent proof — that is, no similarity relies on first assuming the respondent’s guilt. The prosecution distinguishes the alleged poisoning of Simon from the poisoning of the accused’s de facto husband in Perry on the basis that, in Perry, the evidence established that the de facto husband’s symptoms ‘might well have been due to other causes’ and the similar fact relied on — that he was poisoned by arsenic — was not capable of independent proof. While one of the ultimate facts in issue that the prosecution seeks to prove is that the respondent provided poisoned meals to Simon, this fact is not the similarity relied upon to establish coincidence (see [3] above).
63	The prosecution submits:
	When considering the issue of ‘circular’ reasoning in this case, it must be borne in mind that coincidence evidence utilises improbability reasoning. It requires a jury to take into account evidence of multiple events and determine whether they are, overall, explicable by coincidence. The jury’s assessment of one event necessarily affects its assessment of another event, and the collection of events as a whole. Contrary to what his Honour stated in the Ruling, considering the evidence in totality in this way does not involve circular reasoning; it is the very form of reasoning that coincidence evidence employs.
Respondent’s submissions
64	The respondent submits that on charges 1, 2 and 3, she faces a circumstantial case that turns on what inferences may be drawn from expert analysis of historical (and limited) medical records. There is no evidence of any causal, as opposed to temporal, link between Simon consuming a meal prepared by the respondent and falling ill; poisoning was not suspected at the time Simon was suffering from his illnesses; no toxic cause of his illnesses was identified; and at the time of Events 1, 2 and 3, there was no evidence of any animus between Simon and the respondent. As such, the respondent submits that the weight of the circumstantial evidence divorced from coincidence evidence is weak.
65	The respondent submits that the jury would need to engage in circular reasoning of the kind identified in Perry. She submits:
	For the jury to use event 4 in proof that events 1, 2 and 3 were deliberate poisonings, they would first have to reason that event 4 was a deliberate poisoning. Similarly, for events 1, 2 and 3 to rationally and logically bear upon the possibility of deliberate poisoning in event 4, the jury would first have to conclude that Simon Patterson had been deliberately poisoned by the respondent in events 1, 2 and 3.
66	The respondent submits that the seven similarities identified by the prosecution, even if accepted, say nothing about whether or not Simon was poisoned — it is only by incorporating the evidence of poisoning from Event 4 that that inference may be drawn. The probative force that the prosecution assign to the coincidence evidence accrues to Event 4 alone.
Consideration
67	Circular reasoning involves a logical fallacy. An argument’s conclusion is assumed to be true in the reasoning process to that conclusion. In Perry, the accused Mrs Perry was charged with the attempted murder of her husband. It was undisputed at trial that Mr Perry had suffered from chronic arsenic poisoning and lead poisoning. At trial, the prosecution was permitted to lead evidence of three prior events said to enable ‘similar fact’ reasoning. They were:
(1)	the death of the accused’s former husband (Mr Haag) by arsenic poisoning;
(2)	the death of the accused’s brother (Mr Montgomerie) by arsenic poisoning; and
(3)	the death of the accused’s former de facto partner (Mr Duncan) by barbiturate overdose.
68	No sign of arsenic or any heavy metal poisoning was present at Mr Duncan’s autopsy, and indeed his premortem symptoms were contra-indicative of such poisoning. The prosecution invited the jury to conclude that, despite this evidence, Mr Duncan had died from arsenical poisoning, based on the premise that the other instances of poisoning involving Mr Haag, Mr Montgomerie and Mr Perry led inexorably to the conclusion that Mr Duncan had also been poisoned by Mrs Perry and thus the jury could conclude that she had attempted to murder Mr Perry by arsenic poisoning.
69	The logical fallacy in this reasoning is obvious enough. As Gibbs CJ put it:
	It was not established that Duncan had ingested any poison (except of course the barbiturates, with whose consumption the applicant was not shown to have had anything to do). It was necessary for the Prosecution to rely on the other instances of poisoning, including those the subject of the present charges, in an attempt to provide a basis for an inference that Duncan had suffered from arsenical poisoning. In other words, it was necessary to assume the guilt of the applicant of the offences of which she was charged in order to render admissible the evidence regarding the death of Duncan.
70	In the present case, the respondent contended to the trial judge that the prosecution reliance on coincidence reasoning suffered from the same vice; the facts were indistinguishable in any significant sense from Perry and the prosecution’s reliance on coincidence reasoning was circular, thus logically flawed and of little (if any) probative value.
71	The way in which the trial judge dealt with this issue is discussed above at paragraph [56]. We have replicated it below for convenience:
	Does the prosecution’s coincidence evidence in the present case also invite circular reasoning? It is not in dispute that the accused prepared and provided poisoned meals to her lunch guests. What is in dispute is whether she did so deliberately. Is it necessary to first find that the accused deliberately provided poisoned meals to her lunch guests before one could find that the accused provided poisoned meals to Simon Patterson? The answer in my view is ‘Yes’ and, as such, the coincidence evidence does not have significant probative value.
72	This analysis fails to recognise the distinction between the reasoning process applied at first instance in Perry (and set out here in paragraphs [67]–[69]) and the ‘coincidence reasoning’ process urged by the prosecution in this case.
73	‘Coincidence evidence’ is evidence which uses the improbability of two or more events occurring coincidentally to prove that a person performed a particular act or a person had a particular state of mind. It becomes admissible in a criminal case if:
(a)	the court thinks it will have significant probative value when considered either by itself or in conjunction with other evidence in the case; and
(b)	the probative value of the evidence substantially outweighs any prejudicial effect it may have on the accused/defendant.
74	In this case, the amended notice served in accordance with s 98(a) of the Evidence Act, sets out the structure of the prosecution’s coincidence argument (see [3]–[7] above).
75	A summary of the evidence said to support the asserted similarities is set out in Table A of the notice and replicated in part below (at [88]–[106]).
76	Nowhere in the similarities alleged in any of the events identified does the prosecution incorporate into its reasoning process the guilt of the respondent of any of the offences charged. Each similarity relied upon by the prosecution is the subject of independent proof, unlike in Perry.
77	The prosecution asks that the jury consider these similarities together as a combination and then determine whether that combination is explicable by coincidence. Should the jury conclude that the similarities are not so explicable, the prosecution go on to argue that that conclusion, together with other evidence in the case, ought to persuade them that the respondent deliberately poisoned the alleged victims on four separate occasions.
Conclusion on ground 1
78	There is no circularity involved in this reasoning pathway.
Ground 2: Probative value of the coincidence evidence
79	Ground 2 is that the trial judge erred in failing to properly assess the similarities between Events 1 to 4, and therefore failed to properly assess the probative value of the coincidence evidence.
Prosecution’s submissions
80	The prosecution submits that similarity 7 — that is, the temporal connection between the respondent serving food to the affected persons and those persons falling seriously ill — is remarkable, and distinguishes the case from Perry. It describes this similarity as ‘key’:
	The key similarity relied on by the prosecution is similarity 7: after consumption of the food the victims suffered from severe gastrointestinal illnesses. The temporal connection between the accused serving food to the victims and those victims falling seriously ill is remarkable. It sets this case in stark contrast to a case like Perry. For each event, symptoms commenced within 24 hours of the impugned meal being consumed. For Event 3, the illness manifested approximately 30 minutes after the consumption of food. In each instance, unlike Perry, the victims were otherwise in relatively good health prior to the meal. The sudden onset of illness shortly after consuming the accused’s food is all the more powerful in these circumstances.
81	The prosecution submits that similarity 7 must be considered in light of:
(a)	the undisputed fact that Event 4 involved the respondent serving a poisonous meal;
(b)	the otherwise inexplicable nature of Simon’s illnesses in Events 1, 2 and 3;
(c)	the evidence of Professor Bersten that an infective cause for Simon’s illnesses in Events 1, 2 and 3 was highly unlikely, but that ingestion of a toxic substance was possible.
82	The prosecution submits that similarity 6 (the absence of the children) is not an inconsequential similarity. While it may be commonplace for adults to go on outings together and host lunches without children, it was not commonplace among the adults and children in this case. For example, Simon gave evidence that since he and the respondent separated in 2015, the only occasions on which the pair had gone away together without the children were the three occasions the subject of charges 1, 2 and 3 — that is, the three occasions on which Simon became severely ill and required hospitalisation. Further, the absence of the children from the lunch (Event 4) was so notable that the respondent sought to explain it with the pretence of needing to discuss a cancer diagnosis with the adults without the children present.
83	As to similarities 1–5, the prosecution submits that the trial judge did not indicate in the Ruling what weight, if any, he attributed to these similarities. However, taken together, they provide a powerful foundation for coincidence reasoning which was not recognised by the trial judge. The prosecution submits that the evidence discloses that:
(a)	the respondent initiated each activity and arranged to provide the food (similarity 2). All four of the lunch guests expressed some level of surprise about being invited to the respondent’s house for lunch and wondered about the purpose of the invitation. As for Simon, the ‘parents-only’ camping trips organised by the respondent only occurred on three occasions following the separation;
(b)	the respondent prepared the food (similarity 3), and it is undisputed that the lunch involved the respondent serving a poisonous meal to the guests. It is significant that the source of food which precipitated each illness on all occasions was the same person;
(c)	the respondent allocated the food (similarity 4). It is significant that she retained control over the food and subsequently did not suffer the same severe illness that each of the lunch guests and Simon did, notwithstanding the apparent connection between that illness and the food she had prepared and served;
(d)	the respondent appeared to eat a separate meal (similarity 5). This is important in considering the respondent’s opportunity and ability to administer the poison.
Respondent’s submissions
84	The respondent argues that grounds 1 and 2 overlap and relies on her submissions in relation to ground 1. In addition, she submits that similarities 1, 2, 3 and 4 are general in nature and unremarkable. The greater degree of generality, the more difficult it is to demonstrate that the evidence has significant probative value. Putting to one side impermissible tendency reasoning, the suggested similarities do not ‘truly inform the issue of the mental state of the [respondent] on a particular occasion to a significant degree’.
85	In relation to similarity 7, the respondent submits that
	[i]t is not unusual for someone suffering from a gastrointestinal illness to do so within temporal proximity to a meal, whether or not the meal is the cause. Similarly, there is nothing remarkable about the respondent preparing food for Mr Patterson — one might expect she had done so countless times, without him becoming ill, including on some other occasions during the period covered by charges 1, 2 and 3, which was a period when their relationship was good and without any animus.
86	The respondent submits that similarity 6 was properly disregarded by the trial judge.
87	According to the respondent, the trial judge had proper regard to the identified similarities, and, having determined that the coincidence evidence invited impermissible circular reasoning, his Honour was correct to conclude that the evidence did not possess significant probative value.
Consideration
88	The prosecution seeks to utilise coincidence reasoning in two ways: first, to use evidence of Events 1–3 to negate any reasonable possibility of Event 4 being accidental; and secondly, to use evidence of Event 4 in proving that Events 1–3 were also poisonings.
89	In order to determine whether coincidence evidence has ‘significant probative value’, the Court must be satisfied that the similarities relied on are such as to render the evidence probative of the fact that the respondent did the act, or had the state of mind, identified in the notice. Whether the evidence is of significant probative value is a question of fact and degree turning on the particular circumstances of the case. It must be ‘influential in the context of fact-finding’.
90	In our view, the judge’s erroneous conclusion that the coincidence evidence required circular reasoning in order to permit any inferences to be drawn meant that his Honour failed to properly assess the probative value of the similarities between Events 1 to 4, and thereby underestimated their probative value.
Similarity 7
91	We accept the prosecution submission that similarity 7 is of critical importance. The respondent prepared and served a total of seven meals to the five affected persons. Those persons became violently ill a short time after eating those meals. We know that four of the meals contained a deadly toxin.
92	In November 2021, Simon ate a late dinner of penne Bolognese prepared by the respondent and was very ill by the morning. In May 2022, he again became violently ill in the morning having eaten a chicken korma curry prepared by the respondent for dinner the night before. In September 2022, he once again became violently ill shortly after eating a chicken curry wrap prepared by the respondent for his lunch.
93	There is a temporal connection between the ingestion of food prepared by the respondent and the onset of violent gastrointestinal illnesses. While there is no medical evidence establishing that Simon was poisoned on those occasions, the weight to be given to the temporal coincidence is to be assessed by reference to the other similarities.
Similarities 2 to 5
94	As discussed, the prosecution contends that on each occasion the affected persons became violently ill, the respondent orchestrated the event — that is, she initiated the event at which the food was consumed (similarity 2) — and she prepared (similarity 3) and served (similarity 4) the food to the affected persons. Furthermore, on these occasions, the respondent ate food that she allocated to herself separately (similarity 5), in the sense that at no point was she seen to eat food taken from a common pot or plate. The respondent did not suffer the same severe illness as each of the affected persons after eating the food that she prepared.
95	Thus, in relation to the lunch that resulted in the deaths of three of her guests and a life‑threatening illness for the fourth (Event 4), there is clear evidence that the respondent invited the four extended family members and Simon to the lunch; it was an unusual event and was organised for an ostensibly specific purpose; the respondent was solely responsible for preparing the toxic meal; the meal was prepared in a form that allowed for individually prepared and plated servings; and the respondent plated the individual servings. She served four of the beef wellingtons on matching grey plates, which were carried to the table by her guests, and she brought her own beef wellington to the table on a different coloured plate. According to Ian Wilkinson:
	The beef wellington was cooked like a pastie, it was a piece of steak completely encased in pastry and there were mushrooms inside the pastry.
	Heather mentioned to me afterwards that [the respondent] had a different coloured plate and I do remember that. There were four plates the same colour and [the respondent]’s was different. We had large grey coloured dinner plates and [the respondent]’s was a lighter coloured and smaller plate.
	I don’t recall exactly when it was but it was after we got sick and either during the night while we were trying to figure out what was wrong with us, or it was when we were at the Leongatha Hospital, that Heather said to me about [the respondent] having a different coloured plate to us.
96	A luncheon invitation of this kind was unusual. Prior to the lunch, the Wilkinsons had never been to the respondent’s home and it was rare for the respondent to host her in‑laws, although they had been there for a meal with the children approximately one month previously. Apart from Simon, the invitees were surprised to be invited to a meal at the respondent’s home. She told them that she needed to get their advice about a particular, important matter.
97	Events 1 to 3, involving only Simon, are of a different character but share with each other and with Event 4 many of similarities 2 to 5.
98	Turning to Event 1, in his deposition, Simon stated the respondent suggested just the two of them go camping as an alternative to an earlier proposed trip to South Africa together that had not gone ahead due to COVID-19 restrictions. They met at his house the night before to pack for the trip. The respondent brought him dinner.
	At that time, [the respondent] provided me with a Tupperware type container containing penne pasta Bolognese which she said she had made for the kids to eat that night. … We sorted out what we needed to, and [the respondent] left. I finished the packing then ate the pasta quite late in the night and went to bed.
99	As discussed, Simon was very unwell by the next morning, with an illness that led to his hospitalisation.
100	Event 2, a camping trip to Howqua, was organised to make up for the fact that Event 1 had gone so badly wrong. Simon is not clear on who suggested it. On the second night, they ate chicken korma curry with rice.
	[The respondent] prepared the food for serving which she had pre-prepared prior to the trip. This was not the batch we had taste tested but she told me it was made to my preference from the testing. While [the respondent] prepared the food I was attending to the fire and didn’t watch her preparation at all. My understanding was that we were both getting curries cooked to our own preference, but I can’t say that for sure, it was just what I thought was happening. I didn’t see how the curry was packaged.
101	The respondent’s preparation of curries according to individual preference was canvassed at the s 198B hearing. Simon gave evidence that about a week before the trip he was at the respondent’s house and he was asked by her to ‘taste test’ a curry so that she could customise future curry production to the respective tastes of family members.
102	Simon gave evidence at the s 198B hearing that, so far as he could tell, he and the respondent ate the same meal. However, he said that his curry appeared to have been prepared to his preference and that he did not see how the curry was packaged.
103	As to Event 3, the respondent concedes that Simon’s evidence is capable of supporting the similarity that she initiated the catch up that resulted in the two of them going for a walk at Wilsons Promontory:
	[The respondent] suggested that we catch up during the daytime when the children would be at school. I suggested we go to Wilsons Promontory for a walk and [the respondent] offered to bring lunch, to which I agreed. These arrangements were made in that phone call.
104	As for the preparation of the picnic food and its allocation:
	[The respondent] brought lunch which was a chicken curry wrap with salad. I don’t recall if there were mushrooms in the salad. I remember that it was very carefully packed in an insulated bag and with a freezer brick which [the respondent] had packed before I picked her up. [The respondent]’s and my lunch were different.
	My lunch was a pre-prepared wrap with the filling already in it. It was wrapped in aluminium foil, and [the respondent] gave it straight to me. [The respondent]’s lunch was the same ingredients minus the pita bread wrap itself. [The respondent] had her lunch on a plate but I can’t remember if the plate was already served covered in gladwrap or if she put them on the plate from other containers there.
105	Simon was clear that the respondent prepared and ate a separate meal on that occasion.
Similarity 6
106	There is no dispute that the Patterson children were not present on any of the occasions that were followed by severe gastric illnesses. The trial judge considered this to be inconsequential as it was commonplace that adults would organise to meet without children present. However, there is evidence that it was not commonplace in this family. The respondent went to some lengths to explain the absence of the children at what was otherwise a family lunch by concocting a tale about a cancer diagnosis that she needed to discuss in the absence of the children. Simon’s evidence is that after he and the respondent separated in 2015, the only times they went away together without the children were the three occasions on which he became ill.
Value of the evidence
107	Although the defence will no doubt challenge some of the evidence the prosecution puts forward to establish the similarities, particularly Simon’s evidence about Events 1 to 3, we are satisfied that the prosecution is capable of establishing most if not all of the similarities for which it contends. Taken together, these similarities provide a solid foundation for the jury to reason inferentially that it is improbable that the similarities arose coincidentally. On each occasion that the affected persons suffered severe gastrointestinal illness, their symptoms were closely preceded by a meal prepared and served by the respondent, who is known to have served poisonous meals to her guests in Event 4 and not to have been poisoned by what she served herself. There is evidence that those meals, and the meals in Events 1 to 3, were prepared and served in such a way that ensured that only the affected persons consumed them.
108	We therefore consider that the coincidence evidence could rationally affect the assessment of the existence of facts in issue in the case to a significant extent. Put another way, the coincidence evidence, if admitted, could have a significant effect on:
(a)	whether the illnesses suffered by the affected people were caused by consuming food prepared by the respondent; and
(b)	the food prepared by the respondent was poisoned; and
(c)	the respondent deliberately poisoned the food.
Conclusion on ground 2
109	The trial judge erred in assessing the probative value of the similarities in Events 1 to 4.
Ground 3: Prejudicial effect
110	Ground 3 is that the trial judge erred in failing to properly assess the prejudicial effect that the coincidence evidence may have on the respondent.
Prosecution’s submissions
111	The prosecution submits that the trial judge did not address the prejudicial effect of the first use of coincidence evidence in the Ruling. As to the second use, it is submitted that the trial judge’s assessment under s 101 conflates the legitimate, high probative value of the evidence with unfair prejudice. The pathway of reasoning which his Honour labels ‘rank propensity’ is, in fact, phrased another way, legitimate coincidence reasoning, and it would be entirely permissible for the jury to reason in this way.
Respondent’s submissions
112	The respondent submits that the prejudicial effect of the coincidence evidence, namely, the risk of the jury misusing and overvaluing the evidence in their assessment of charges 1, 2 and 3, even after carefully formulated directions, is high. Moreover, directing on the different, permissible uses of the evidence and maintaining the critical importance of separate consideration, will be a difficult task. Following and applying those directions would require an unrealistic level of mental gymnastics from a jury. This is especially so when the body of evidence for Events 1, 2 and 3 is weak, while the evidence pertaining to Event 4 involves admissions and other incriminating conduct.
Consideration
113	This ground is directed at the judge’s assessment of the prejudicial effect that the admission of the coincidence evidence may have on the respondent. Section 101(2) of the Evidence Act relevantly provides that coincidence evidence adduced by the prosecution cannot be used against an accused unless the probative value of the evidence substantially outweighs any prejudicial effect it has on the accused.
114	For the reasons we have set out under ground 2, we regard the probative value of the coincidence evidence as significant, having regard to the other evidence to be adduced in the case.
115	Section 101(3) requires a balancing exercise, the result of which is determined by a subjective evaluation of the ‘probative value’ and ‘any prejudicial effect’ on an accused person. The phrase does not include prejudice arising from a ‘legitimate tendency to inculpate’, but conveys the notion of harm to an accused’s interest arising from a risk that the jury will use evidence ‘improperly in some unfair way’.
116	Prejudice includes the risk that evidence will be given too much weight by the jury (‘reasoning prejudice’) or that its emotional impact may destroy the jury’s objectivity (‘emotional prejudice’).
117	In this case, the trial judge expressed his conclusions on s 101 as follows:
	Even if the coincidence evidence has significant probative value, I consider that it fails to clear the additional hurdle that is created by s 101. A finding that the accused had deliberately poisoned Don Patterson, Gail Patterson, Ian Wilkinson and Heather Wilkinson would be a finding that would create a very significant risk of the jurors misusing or overvaluing the evidence in relation to the charges concerning Simon Patterson. As regards the former risk, a striking passage in Report 26 of the Australian Law Reform Commission, quoted with approval by McHugh J in Papakosmas v R, bears repeating: 
	By risk of unfair prejudice is meant the danger that the fact-finder may use the evidence to make a decision on an improper, perhaps emotional, basis, ie on a basis logically unconnected with the issues in the case. Thus evidence that appeals to the fact-finder's sympathies, arouses a sense of horror, provokes an instinct to punish, or triggers other mainsprings of human action may cause the fact-finder to base his decision on something other than the established propositions in the case. Similarly, on hearing the evidence the fact-finder may be satisfied with a lower degree of probability than would otherwise be required.
118	After anxious consideration, we are not satisfied that the prosecution has demonstrated that the probative value of the coincidence evidence substantially outweighs the prejudicial effect it may have on the respondent.
119	There is no doubt that the coincidence evidence bears directly on all four alleged poisoning events. Used permissibly, it is capable of bearing on the likelihood that the respondent deliberately poisoned her husband on three occasions and that the admitted poisoning of the dinner guests on the fourth occasion was deliberate. A prosecutor may ask the jury: what are the chances that these seven gastrointestinal catastrophes were unrelated medical episodes (charges 1, 2 and 3) or culinary misfortunes (charges 4–7)? The respondent prepared the food, she served it, and, on each occasion, grave illness or death followed.
120	We have no difficulty in concluding that, used permissibly, at least in regard to the admitted poisonings at the lunch on 29 July 2023, the coincidence evidence assists the prosecution in resisting a defence of simple culinary accident. We pause to observe that regardless of the coincidence evidence, we consider the prosecution case on those admitted 29 July 2023 poisonings to be extraordinarily strong. The probative value of the impugned evidence must be viewed against that background insofar as charges 4, 5, 6 and 7 are concerned.
121	Insofar as charges 1, 2 and 3 are concerned, the other evidence to be adduced by the prosecution is of a different quality. There is no direct evidence that Simon was poisoned on any of the three charged occasions. There is no direct medical or toxicological evidence that on any of these occasions he was in fact poisoned, and, without descending into detail, there is only the slimmest medical opinion that his symptoms on the first two occasions could more likely be explained by toxins than by infection. On the third occasion, poisoning by death cap mushrooms could be all but excluded. Further, the third illness may simply have been a consequence of the second illness.
122	Whilst there was some evidence of pre-existing acrimony between the respondent and Simon Patterson, it appears to be relatively inconsequential.
123	Without resort to coincidence reasoning, there is no case of attempted murder on any of charges 1–3. The coincidence evidence relating to Events 1 to 4 offers quite considerable assistance to the prosecution in advancing its case that the food served by the respondent was deliberately poisoned by her. As we have said, its probative value is significant — in other words, high. However, it must be balanced against any prejudicial effect it may have on the respondent, and it must win that exercise by a substantial margin. 
124	Despite the significant probative value of the coincidence evidence, we consider there is a considerable risk, particularly in relation to charges 1 to 3, that the jury will experience both reasoning prejudice and emotional prejudice. This is a case which has excited widespread public interest. Three people are dead, another nearly died. As Priest JA has concluded, the evidence that the lunch guests were poisoned
	will conjure up a highly suspicious, prejudicial atmosphere in which the presumption of innocence will tend to be obscured in the minds of any jury.
125	This is ‘emotional prejudice’.
126	In the absence of any real medical or toxicological support on charges 1 to 3, we consider that there is a really substantial risk that the jury may use the fact that poison was administered at the lunch on 29 July 2023, to reason along the lines that ‘if she deliberately poisoned her lunch guests, she must have deliberately poisoned her husband on the earlier occasions’. To a jury of non-lawyers, we consider that this type of impermissible propensity reasoning would be nigh on irresistible, and, consciously or not, used as a substitute for the absence of any proper scientific evidence. This is ‘reasoning prejudice’.
Conclusion on ground 3
1	
127	We consider the degree of risk of an unfair trial, at least of charges 1 to 3, in these circumstances is high. Directions which attempt to explain the legitimate use of coincidence reasoning insofar as it relates to all charges and yet which caution against propensity reasoning, circular reasoning, or even unauthorised tendency reasoning, are likely to confuse rather than clarify matters. We are not satisfied that the probative value of the coincidence evidence relating to Events 1, 2 and 3 substantially outweighs the prejudicial effect it may have on the respondent.
128	For these reasons, it was correct for his Honour to rule that the evidence sought to be adduced for coincidence reasoning purposes was inadmissible for those purposes. Obviously a good deal of that evidence relates to charges 4, 5, 6 and 7 and will be admissible for other purposes. It was thus correct for his Honour to sever the indictment.
PRIEST JA:
Introduction
129	On 29 July 2023, Erin Patterson, the respondent, hosted a lunch at her home in Leongatha, at which she served each of her four adult guests an individual Beef Wellington, a dish consisting of steak covered in mushrooms and encased in pastry.  By 5 August 2023, three guests — Gail and Donald Patterson, and Heather Wilkinson — had died from death cap mushroom poisoning.  Although the fourth lunch guest, Ian Wilkinson, became perilously ill — also from death cap mushroom poisoning — he survived.
130	The prosecution alleges that the respondent deliberately poisoned her guests by using death cap mushrooms in the Beef Wellingtons she served.  As a result, an indictment filed in the Supreme Court charges the respondent with the murders of Heather Wilkinson, and Gail and Donald Patterson (charges 5, 6 and 7 respectively), and with the attempted murder of Ian Wilkinson (charge 4).  The alleged deliberate poisoning of these four victims has been described by the prosecution as ‘Event 4’.
131	Prior to the deadly lunch, the respondent’s husband, Simon Patterson, from whom she had separated in 2015, became extremely ill on three occasions — 16 November 2021, 25 May 2022 and 6 September 2022 — after eating meals prepared by the respondent.  The prosecution alleges that the respondent poisoned her husband on those three occasions intending to kill him.  As a result, the indictment contains three charges of attempted murder relating to these three occasions (charges 1, 2 and 3).  The alleged deliberate poisonings of Simon Patterson on those occasions have been described by the prosecution as ‘Event 1’, ‘Event 2’ and ‘Event 3’ respectively.
132	In anticipation of a trial on the indictment, on or about 24 January 2025 the prosecution filed an amended Coincidence Notice pursuant to s 98(1)(a) of the Evidence Act 2008 (‘the Act’), containing the particulars set out below, giving notice to the respondent that the prosecution intends to rely on coincidence reasoning (‘the notice’).
133	By a ruling dated 14 March 2025, the trial judge ruled the proposed coincidence evidence to be inadmissible, and ordered that charges 1, 2 and 3 on the indictment be severed from charges 4, 5, 6 and 7 (‘the ruling’ or ‘the interlocutory decision’).
134	Pursuant to certification of the trial judge under s 295(3)(b) of the Criminal Procedure Act 2009 (‘CPA’), given on 19 March 2025, the Director of Public Prosecutions seeks leave to appeal against the interlocutory decision — ‘namely the refusal to admit coincidence evidence and severance of indictment’ — on three grounds, which assert that the trial judge erred:
1	… in finding that the coincidence evidence invites circular reasoning, and is therefore inadmissible on the basis of Perry v R (1982) 150 CLR 580.
2	… in failing to properly assess the similarities between Events 1 to 4, and therefore failed to properly assess the probative value of the coincidence evidence.
3	… in failing to properly assess the prejudicial effect that the coincidence evidence may have on the accused.
135	In my opinion, the judge’s ruling was correct.  The Director’s application for leave to appeal against the interlocutory decision must be refused.
The notice
136	Before turning to the evidence relied upon by the prosecution, it is convenient to note that the notice sets out the prosecution’s intention
1.	… to adduce evidence which will be relied upon to establish that the accused did a particular act and/or had a particular state of mind namely:
1.1	Deliberately poisoned Simon Patterson on 16/11/21 (Event 1);
1.2	Deliberately poisoned Simon Patterson on 25/5/22 (Event 2);
1.3	Deliberately poisoned Simon Patterson on or about 6/9/22 (Event 3);
1.4	Deliberately poisoned Gail Patterson on 29/7/23 (part of Event 4);
1.5	Deliberately poisoned Donald Patterson on 29/7/23 (part of Event 4);
1.6	Deliberately poisoned Heather Wilkinson on 29/7/23 (part of Event 4);
1.7	Deliberately poisoned Ian Wilkinson 29/7/23 (part of Event 4); and
1.8	Intended to deliberately poison Simon Patterson on 29/7/23 (part of Event 4).
on the basis that, having regard to the similarities in the events and/or circumstances in which they occurred, it is improbable that each of the alleged victims suffered severe gastrointestinal illnesses after having consumed food prepared for them by the accused coincidentally.
2.	The facts in issue that the Prosecution seeks to prove by relying on the improbability of coincidence are:
2.1	The illnesses suffered by the victims in events 1 to 4 were caused by the victims consuming food prepared by the accused.
2.2	The food prepared by the accused for each event was poisoned; and
2.3	The accused deliberately poisoned the food for each event.
3.	The Prosecution relies on the following points of similarity (“S”) between the events and the circumstances in which they occurred:
3.1	S.1: the accused was related by marriage to each victim.
3.2	S.2: the accused initiated/instigated each activity with Simon Patterson, and the four lunch guests.
3.3	S.3: the accused prepared the food.
3.4	S.4: the accused allocated the food.
3.5	S.5: the accused ate a separate meal from Simon Patterson, and the four lunch guests.
3.6	S.6: the accused’s two children, [redacted] and [redacted], were not present at the time the food was served to Simon Patterson, and the four lunch guests.
3.7	S.7: after consumption of the food each of Simon Patterson and the four adult family relatives suffered from severe gastrointestinal illnesses; and
3.8	S.8: at a time before or shortly after each event, the accused used a computer or other electronic device to access online content relating to poisons.
The prosecution case
Charges 4 to 7
137	With respect to charges 4, 5, 6 and 7, the prosecution case is that the respondent invited her husband, Simon Patterson, his parents, Donald Patterson and Gail Patterson, and his aunt and uncle, Ian Wilkinson and Heather Wilkinson, to lunch on 29 July 2023.  Although Simon Patterson initially accepted the invitation, he sent a text message to the respondent the evening before the lunch telling her that he would not be attending.
138	On the morning of 29 July 2023, Donald and Gail Patterson picked up the Wilkinsons.  They travelled together to the respondent’s house in Leongatha, arriving at around 12.30 pm.  At some point the respondent served each guest a lunch consisting of individual Beef Wellingtons, mashed potato and green beans.  Ian and Heather Wilkinson ate their entire portion.  Gail Patterson ate approximately half of her serve and gave the rest to her husband, who also consumed his own portion.  The respondent also ate a Beef Wellington that she served to herself.  After lunch, the respondent told her guests that she had cancer and asked for advice on whether to tell the children.
139	Soon after the lunch, each of the four guests suffered serious gastrointestinal illness.  They were hospitalised and eventually diagnosed with death cap mushroom poisoning.  The respondent was also hospitalised, but was not diagnosed with death cap mushroom poisoning.  Her symptoms were mild compared to those suffered by her lunch guests.  Gail Patterson and Heather Wilkinson died on 4 August 2023, and Donald Patterson died on 5 August 2023.  Ian Wilkinson, who had been admitted to hospital on 1 August 2023 and received intensive medical treatment, was discharged to a rehabilitation ward on 11 September 2023.
140	Prior to the fatal lunch, Simon Patterson had, as I have mentioned, become ill on three occasions after eating food given to him by the respondent.  Drawing on the Summary of Prosecution Opening, dated 24 February 2025, the judge set out the evidence relied upon to support the three charges of attempted murder involving Simon Patterson.  Save to make reference to key pieces, it is unnecessary to recapitulate the evidence in detail.
Charge 1
141	Charge 1, Event 1, relates to an occasion on Tuesday, 16 November 2021, when the respondent visited Simon Patterson’s house in Korumburra, to pack for a hiking trip to Wilsons Promontory which they had arranged for the following day.  The respondent gave him a Tupperware container containing penne pasta Bolognese.  Simon Patterson ate the pasta before going to bed.  The next morning he felt unwell.  He went to pick up the respondent at her home where he vomited multiple times.  They then left on their hiking trip.  The respondent drove because her husband was unwell.  On the journey Mr Patterson suffered vomiting and diarrhoea and had to use public toilets multiple times.  During their overnight stay at booked accommodation, Simon Patterson continually vomited and had diarrhoea.
142	On Friday, 19 November 2021, the respondent took her husband to the Leongatha Hospital, where he was diagnosed with severe dehydration due to gastroenteritis and admitted.  Blood test results showed he was suffering from acute renal impairment.  He was discharged the following morning.  On 21 November 2021, Mr Patterson returned to Leongatha Hospital, and was then transferred to Monash Medical Centre, where testing revealed markedly elevated calprotectin, consistent with significant bowel inflammation.  He remained in hospital as his renal function recovered and was discharged on 27 November 2021.
143	Extensive testing did not identify a cause of the vomiting and diarrhoea.  Faecal specimens were negative for faecal pathologies and did not reveal underlying bowel pathology.  The cause of his acute renal failure was presumed to be acute tubular necrosis secondary to dehydration due to the preceding gastroenteritis.  Ultimately, however, treating doctors were unable to determine the underlying cause of Simon Patterson’s illness.
Charge 2
144	On Tuesday, 24 May 2022, Simon Patterson and the respondent went camping near Howqua.  On the second night of this trip, 25 May 2022, the respondent and her husband ate chicken korma curry with rice which she had prepared for dinner.  Early the following morning, 26 May 2022, Mr Patterson started to feel sick and experienced vomiting and diarrhoea.  The respondent drove her husband to Mansfield Hospital, where he was treated with intravenous fluids and anti-nausea medication.  Since his vital signs were unremarkable, he was discharged later that day.
145	Early in the morning on 29 May 2022, however, Simon Patterson felt weak and was having trouble making it to the bathroom.  He called the respondent for help at 5.20 am.  The respondent went to his house and called an ambulance at 5.45 am.  Mr Patterson, whose vital signs were significantly abnormal and who had low blood pressure, was taken to Monash Casey Hospital, where he was admitted with haemodynamic shock.  Blood testing revealed severe lactic metabolic acidosis, hypothermia, multi-organ failure, marked elevation of ALT (a liver enzyme) suggesting liver ischemia and severe sepsis.  A CT scan demonstrated severe bowel pathology consistent with established necrosis.  Simon Patterson was admitted to the intensive care unit, intubated and treated with various medications including broad spectrum antibiotics.  He was critically ill and clinically very unstable, requiring multi-system support.  Among other procedures, on 29 May 2022 Mr Patterson underwent a resection (removal) of 132 centimetres of ischemic small bowel due to necrosis.
146	Despite very extensive testing, doctors were unable to determine the cause of Mr Patterson’s illness.  On 14 June 2022 he was extubated; and, on 22 June 2022, he was transferred to a rehabilitation centre, having spent 24 days stay in hospital.  He remained in rehabilitation until 8 July 2022, and then went to stay at the respondent’s home while he recovered.
147	Whilst staying with the respondent, Simon Patterson again became ill.  On 22 July 2022, he ate beef stew with rice prepared by the respondent.  Shortly after midnight the following morning, 23 July 2022, he started vomiting and suffering from diarrhoea.  Ultimately he was taken to the Monash Medical Centre, where he remained for a few days.  Further extensive medical testing was undertaken, as part of which an infective gastroenteritis was investigated, but no infective cause found.  Doctors were unable to determine the cause of Mr Patterson’s illness.
148	On 25 August 2022, Simon Patterson consulted Associate Professor Mills, who considered the most plausible answer for why Mr Patterson had become ill was that he had contracted an infection, Clostridium Difficile, following a severe acute gastrointestinal illness.
Charge 3
149	After Simon Patterson returned home, he and the respondent continued to have contact.  In late August or early September 2022, the respondent suggested to Mr Patterson that they catch up.  On Tuesday, 6 September 2022, they went for a walk at Wilsons Promontory.  The respondent served Mr Patterson a pre-prepared chicken curry wrap in aluminium foil.  Shortly after eating the wrap, Mr Patterson began to feel unwell, and suffered diarrhoea.  He then started to vomit and suffered diarrhoea during the car trip home.  They went to his parents’ home, where he continued to vomit.  His parents called an ambulance.
150	On the way to the Monash Casey Hospital, where he was admitted to the intensive care unit, Simon Patterson suffered a ‘seizure’, requiring intravenous medication, and was in a reduced conscious state.  In hospital, he went into polymorphic ventricular tachycardia (a potentially life-threatening heart rhythm) and was intubated.  He was treated in hospital for three days and was discharged on 9 September 2022.  A routine stool sample that he had provided on 6 September 2022, prior to eating the wrap, indicated no obvious bacteria, parasites or inflammation in his intestines.  Once more, treating doctors could not determine the cause of Mr Patterson’s illness.
Subsequent medical analysis of Simon Patterson’s illnesses
151	Intensive care specialist Professor Andrew Bersten examined Simon Patterson’s medical files in 2024 to determine whether there was a unifying diagnosis across his multiple admissions to hospital between 2021 and 2022, relevant to charges 1, 2 and 3.
152	After reviewing the files, Professor Bersten noted that the cause of the gastrointestinal symptoms on each occasion, particularly in the first and second illnesses, was acute in nature (severe and sudden in onset).  The cause itself could not be positively identified, however, despite reasonably extensive investigation and testing.  Nevertheless, some potential causes could be eliminated or deemed unlikely.  Hence, according to Professor Bersten, a chronic bowel condition was unlikely, and an infective cause of the illnesses could not be identified.  In Professor Bersten’s view, Simon Patterson’s second illness, which led to an extensive bowel resection and a prolonged ICU admission, complicates interpretation of the illnesses that followed.
153	With respect to Simon Patterson’s first illness in November 2021, Professor Bersten was of the view that it was likely that there was either a toxic or an infective cause.  Ingestion of a toxic substance is possible, but Professor Bersten could not suggest what that substance could be.  Significantly, Professor Bersten was of the opinion that the lack of liver damage is inconsistent with amatoxin poisoning.  (Amatoxins are found in amanita phalloides — death cap mushrooms — and exhibit high human toxicity.  They can be lethal due to interruption of metabolic processes, which can cause extensive necrosis, leading to irreversible structural tissue damage particularly in the liver and kidneys.)
154	Considering the available evidence, Professor Bersten expressed the view that the cause of Simon Patterson’s second illness was uncertain, albeit that it was likely caused either by a toxic or an infective cause.  No infective cause for the illness was identified, but this could not be definitively excluded.  Ingestion of a toxic substance was possible, but Professor Bersten could not suggest what that substance could be.  Once more significantly, Professor Bersten expressed the view that the pattern and rapid resolution of Simon Patterson’s acute liver damage during the second illness presentation was not consistent with typical amatoxin poisoning.
155	As to the third illness, Professor Bersten noted Simon Patterson presented to Casey Hospital on 6 September 2022 with extremely low potassium, following an abnormal ECG and abnormal rhythm episodes.  Professor Bersten considered that Simon Patterson had potassium depletion for weeks to months prior to the 6 September admission which was not evident from the testing.  Further, the vomiting and diarrhoea earlier that day acutely depleted Simon’s total potassium, leading to an extremely low blood potassium, which then in turn led to the heart rhythm disturbance.  Professor Bersten was not able to pinpoint the cause of Mr  Patterson’s chronic potassium deficit, but found it was consistent with ongoing bowel losses and the bowel resection he required in May 2022.
156	When giving evidence pre-trial pursuant to s 198B of the CPA, Professor Bersten said that ‘there are multiple causes of gastroenteritis’.  It is ‘more like a syndrome’ and is ‘not a single entity’.  He refers to it as a ‘gastrointestinal disturbance or upset’.  Gastroenteritis may result from an ‘infective cause’, such as ‘a viral infection of the gastrointestinal tract’.  It may also result from bacterial infection.  Some bacteria ‘will produce toxins and it’s the toxin that causes the syndrome’.  A ‘metabolic imbalance’ may also be responsible.  Further, Professor Bersten’s evidence was in effect that the fact that no infective cause was found did not necessarily mean that the condition had not resulted from such a cause.  It is possible that by the time testing was carried out, an infective cause had been resolved or eliminated by the body, with gastrointestinal symptoms continuing.  Professor Bersten also said that Simon Patterson might have had an infective illness that was not detected by the relevant PCR test, because even though it is an ‘extremely sensitive’ test, you ‘may find some small percentage of infective causes that are not picked up by PCR’.  Significantly, Professor Bersten made it clear that the mere fact that a person develops gastrointestinal symptoms within hours of eating a meal does not mean the meal is responsible for the illness: ‘No it doesn’t mean that, it could be but it doesn’t mean that no’.
The defence case
157	On charges 1, 2 and 3, the respondent denies deliberately poisoning Simon Patterson.
158	With respect to charges 4, 5, 6 and 7, the respondent does not dispute that the death of Heather Wilkinson, Gail Patterson and Donald Patterson, and the serious illness suffered by Ian Wilkinson, are consistent with amatoxin poisoning, but she denies deliberately poisoning them.
Submissions to the trial judge
Prosecution submissions
159	Prosecuting counsel submitted to the trial judge that, taking it at its highest, the evidence supported each of the alleged similarities between Events 1 to 4.  Counsel submitted that those similarities were uncanny, especially having regard to the family relationship between the respondent and the alleged victims; the fact that they all fell seriously ill after eating meals prepared by the respondent; and the respondent was accessing information on poisons before or shortly after each event.  Counsel relied on the observations of Gibbs CJ in Perry concerning the improbability of coincidence accounting for a series of poisonings within a suspect’s circle of associates.  Prosecuting counsel submitted that the uncanny similarities between Events 1, 2, 3 and 4 by themselves gave the evidence significant probative value.  But, when considered in combination with the other evidence on which the prosecution relied (including incriminating conduct), the coincidence evidence clearly passed the test in s 98 of the Act.
160	Further, prosecuting counsel submitted that any risk of unfair prejudice could be cured by directions.  The jury could be expected to follow directions and not engage in rank propensity reasoning.
161	In response to a submission by defence counsel, prosecuting counsel submitted that, in relation to S.7, the prosecution was not assuming what it was setting out to prove; that is, that meals served by the respondent to Simon Patterson were poisoned.  Rather, the prosecution was relying on the timing of the severe illnesses, in that Simon Patterson and each of the lunch guests fell ill soon after eating meals prepared by the respondent.
Defence submissions
162	Defence counsel submitted that the evidence did not bear out each of the alleged similarities in relation to Events 1 to 4.  In particular, the evidence did not establish that the respondent suggested all the trips with Simon Patterson, or that she allocated all the meals to him or ate separate meals to him.  In relation to Event 4, the respondent did not allocate the meals or eat a separate meal.  Moreover, the meals constituting Events 1, 2 and 3 were not proximate to the meal constituting Event 4.
163	Even assuming the alleged similarities, defence counsel submitted, they were unremarkable.  Hence, the coincidence evidence did not have significant probative value.  Counsel highlighted the limitations of the medical evidence in relation to Simon Patterson’s illnesses.  That evidence did not exclude the real possibility that Simon Patterson suffered from infections or that his illness following Event 3 was attributable to the severe illness after Event 2 (as the prosecution conceded might have been the case with Simon Patterson’s illness in July 2022).
164	Defence counsel also relied on Perry.  Counsel submitted that if the jury determined that the respondent deliberately poisoned her lunch guests, the jury was likely to have an emotional response against the respondent; that is, they would misuse the evidence, and would jump to the conclusion that the respondent had served poisoned meals to Simon Patterson, thereby overvaluing the evidence.  Counsel submitted that directions would not cure the overwhelming prejudice.
The ruling
165	The judge said that, in conducting his analysis of the competing submissions, he would assume that the evidence bears out each of the alleged similarities, save for S.8.
166	With regard to S.8 — ‘at a time before or shortly after each event, the accused used a computer or other electronic device to access online content relating to poisons’ — the judge said that there are only two admissible instances of the respondent allegedly accessing online information about poisons, they being 28 April 2022 (shortly after Event 2) and 4 May 2023 (approximately two weeks before Event 4), both relating to death cap mushrooms.  Consequently, the judge observed, there is no admissible evidence that at a time ‘before’ or ‘shortly after’ Event 1 (16 November 2021) the respondent used a computer or other electronic device to access online content relating to poisons.  While the online access on 28 April 2022 in relation to death cap mushrooms was ‘before’ Event 3, it was not sufficiently proximate to Event 3 to be of any moment.  In any event, the judge said, ‘the medical evidence regarding Events 1 to 3 is that the symptoms exhibited by Simon Patterson were inconsistent with typical death cap mushroom poisoning’.  Accordingly, the judge said, he disregarded S.8 in assessing the probative value of the coincidence evidence.
167	Of the remaining similarities, the judge considered S.6 — ‘the accused’s two children … were not present at the time the food was served to Simon Patterson, and the four lunch guests’ — to be ‘inconsequential’, since it ‘is commonplace for adults to go on outings together and host lunches without children being present’.
168	With respect to the remaining six ‘similarities’ — S.1, S.2, S.3, S.4, S.5 and S.7 — the judge expressed the view that what most assists the prosecution’s submission that the coincidence evidence has significant probative value is ‘the fact that shortly after eating meals prepared by the [respondent], Simon Patterson and the lunch guests suffered severe gastrointestinal illnesses (and the [respondent] did not)’.
169	Turning to Perry — decided under the common law rather than ss 98 and 101 of the Act — the judge noted that the High Court was unanimous that certain alleged similar fact evidence should not have been admitted.
170	Ultimately, the judge concluded that the coincidence evidence upon which the prosecution sought to rely lacked ‘significant probative value’ because it invited ‘circular reasoning’.  He explained:
	Does the prosecution’s coincidence evidence in the present case also invite circular reasoning?  It is not in dispute that the [respondent] prepared and provided poisoned meals to her lunch guests.  What is in dispute is whether she did so deliberately.  Is it necessary to first find that the [respondent] deliberately provided poisoned meals to her lunch guests before one could find that [she] provided poisoned meals to Simon Patterson?  The answer in my view is ‘Yes’ and, as such, the coincidence evidence does not have significant probative value.
171	Having determined that the coincidence evidence lacked significant probative value, the judge then turned to the requirements of s 101(2) of the Act, and concluded that the probative value of the evidence did not substantially outweigh any prejudicial effect it may have on the respondent.  He said that a finding that the respondent had deliberately poisoned Donald Patterson, Gail Patterson, Ian Wilkinson and Heather Wilkinson, would be a finding ‘that would create a very significant risk of the jurors misusing or overvaluing the evidence in relation to the charges concerning Simon Patterson’.
172	The judge cited a passage from Papakosmas, and said:
	Would the jurors in the present case be as rigorous in applying the criminal standard of proof as they should be, if they formed the view that the [respondent] had deliberately and fatally poisoned Simon Patterson’s mother, father and aunt and had deliberately and nearly fatally poisoned his uncle?  Would the jurors be able to dispassionately assess the evidence specific to Charges 1–3 and pay full heed to the limitations of the medical evidence regarding the possible causes of Simon Patterson’s severe illnesses?  Moreover, would the jurors be able to resist rank propensity reasoning such as ‘[s]he deliberately poisoned Simon Patterson’s parents, uncle and aunty: isn’t it likely, then, that she deliberately poisoned Simon Patterson?’  All of these dangers or risks could, of course, be the subject of directions, but the guiding principle that jurors can generally be trusted to abide by directions admits of exceptions.  Even if the impugned evidence is credited with significant probative value, I am not persuaded that its probative value substantially outweighs the significant danger or risk of unfair prejudice to the accused.  
173	Ultimately, the judge ordered that charges 1, 2 and 3 on the indictment be severed from charges 4, 5, 6 and 7, ‘as it would be unfair to hear all the charges together’.
The applicant’s submissions in this Court
174	Counsel for the applicant submitted that the judge was wrong to find that the coincidence evidence relied on by the prosecution invited circular reasoning, and erred in finding that the evidence in the present case suffered from the kind of circularity as the impugned evidence in Perry.  The applicant’s counsel submitted that, when considering the issue of ‘circular’ reasoning in this case, it must be borne in mind that coincidence evidence utilises improbability reasoning.  It requires a jury to take into account evidence of multiple events and determine whether they are, overall, explicable by coincidence.  The jury’s assessment of one event necessarily affects its assessment of another event, and the collection of events as a whole.  Contrary to what the judge found, considering the evidence in totality in this way does not involve circular reasoning: it is the very form of reasoning that coincidence evidence employs.
175	With respect to S.7 — ‘after consumption of the food each of Simon Patterson and the four adult family relatives suffered from severe gastrointestinal illnesses’ — counsel for the applicant submitted that the temporal connection between the respondent serving food to the alleged victims and the alleged victims falling seriously ill is remarkable, and sets the present case apart from a case like Perry.  The temporal connection between consuming the respondent’s food and becoming ill is particularly significant for charges 1, 2 and 3.  Further, contrary to what the judge found, S.6 — the children were not present when the food was served — is not ‘inconsequential’.  Simon Patterson’s evidence is that, since he and the respondent separated in 2015, the only times he and the respondent had gone away together without the children were the three occasions the subject of charges 1, 2 and 3.  Every time he and the respondent went away together without the children after 2015, Simon Patterson became severely ill and required hospitalisation.
176	The applicant’s counsel also submitted that S.1 demonstrates that each event occurred within the same familial group, with a common connection being the respondent.  And S.2 to S.5, taken together, counsel submitted, provide a powerful foundation for coincidence reasoning, which was not recognised by the trial judge.  The combination of circumstances demonstrates that on each occasion that the victims suffered severe gastrointestinal illness, their symptoms were closely preceded by a meal prepared and served by respondent, who is known to have served the poisonous meal in Event 4.  Those meals were prepared and served in such a way that ensured only the intended victims consumed the contents.  Each time, the respondent did not suffer the same illness.
177	Counsel for the applicant submitted that the prosecution seeks to utilise coincidence reasoning in two distinct, but related ways: first, the prosecution seeks to adduce evidence of Events 1 to 3 to negate any reasonable possibility of Event 4 being an accidental poisoning; and, secondly, to utilise evidence of Event 4 to prove that events 1, 2 and 3 were also poisonings.  Any prejudicial effect from the first use was not dealt with by the judge.  Counsel submitted that the trial judge found the prejudicial effect of the second use of the coincidence evidence necessitated exclusion under s 101(2).  The pathway of reasoning that the judge labelled ‘rank propensity’ when making the assessment required by s 101(2) wrongly conflated the legitimate, high probative value of the evidence, with unfair prejudice.  Finally, counsel submitted, there is no basis to conclude that the jury would overvalue this evidence, or apply a lower standard of proof to charges 1, 2 and 3, or that they would be unable to heed judicial directions on the permissible use of the coincidence evidence.
178	I will later return to some more of the oral submissions made by senior counsel for the applicant.
The respondent’s submissions in this Court
179	Citing Gale, the respondent’s counsel submitted that, in order to determine whether coincidence evidence has ‘significant probative value’, the Court must first be satisfied that the similarities relied on are such as to render the evidence probative of the fact that the respondent did the act, or had the state of mind, identified in the notice.  The question whether the evidence is of significant probative value is one of fact and degree turning on the particular circumstances of the case.  It is not sufficient that the coincidence evidence is of significant probative value: the probative value of the evidence must also substantially outweigh any prejudicial effect it may have on an accused person.  Counsel for the respondent submitted that the ‘high barriers’ to the admission of coincidence evidence recognise that the admission of evidence as cross-admissible between counts on an indictment — where it would not otherwise be — intrudes upon the fundamental principles of the presumption of innocence and separate consideration, and that such evidence is inherently liable to misuse.
180	With respect to the first proposed ground, counsel submitted that on charges 1, 2 and 3 there is no evidence of any causal (as opposed to temporal) link between Simon Patterson consuming a meal prepared by the respondent and falling ill, and no evidence that any of the meals were poisoned, deliberately or otherwise.  Indeed, poisoning was not suspected at the time Mr Patterson was suffering from the three illnesses, and no toxic cause was identified.
181	Counsel for the respondent submitted that, for the jury to use Event 4 in proof of Events 1, 2 and 3, they would first have to reason that Event 4 was a deliberate poisoning.  Similarly, for Events 1, 2 and 3 to rationally and logically bear upon the possibility of deliberate poisoning in Event 4, the jury would first have to conclude that Simon Patterson had been deliberately poisoned by the respondent in Events 1, 2 and 3.  Counsel submitted that the circular reasoning discussed in Perry applied to both the prosecution’s first use and second use of the evidence.  The seven similarities identified by the applicant, even if accepted, say nothing about whether or not Simon Patterson was poisoned.  It is only incorporating the evidence of deliberate poisoning from Event 4 that allows for that inference to be drawn.  In reality, counsel submitted, the probative force that the prosecution assigns to the coincidence evidence accrues to Event 4 alone.
182	As to proposed ground 2, counsel for the applicant submitted that, in conducting the analysis required by s 98 of the Act, the trial judge proceeded on the assumption that the evidence bore out each of the alleged similarities.  The prosecution seeks to use the coincidence evidence to establish the respondent’s intention; that is, that she deliberately poisoned all five alleged victims.  Putting to one side impermissible tendency reasoning, the suggested similarities do not ‘truly inform the issue of the mental state of the accused on a particular occasion to a significant degree’.
183	Counsel for the respondent submitted that it is not the number of similarities that is important, but their probative force.  That Simon Patterson fell ill after eating food prepared by the respondent does not alone imbue the coincidence evidence with significant probative value.  It is not unusual for someone suffering from a gastrointestinal illness to do so within temporal proximity to a meal, whether or not the meal is the cause.  Similarly, there is nothing remarkable about the respondent preparing food for Mr Patterson.  One might expect she had done so countless times, without him becoming ill.
184	The respondent’s counsel submitted that S.6 was properly disregarded by the judge.  Similarly, S.1, S.2, S.3 and S.4 are general in nature and unremarkable.  Counsel submitted that the greater the degree of generality, the more difficult it will be to demonstrate significant probative value, or that the probative value of evidence substantially outweighs its prejudicial effect.  The judge was correct to find that the coincidence evidence invited impermissible circular reasoning and did not pass the significant probative value test.
185	Dealing with proposed ground 3, the respondent’s counsel submitted that the expression ‘prejudicial effect’ in s 101(2) of the Act is directed to the risk that the jury will use the evidence improperly in some unfair way.  Counsel submitted that the facts of this case raise for consideration the extent of that seductive but erroneous reasoning process in assessing the true probative value of the evidence, and in assessing the risk of misuse of the coincidence evidence.  Disentangling the permissible uses of the evidence from the impermissible uses will be a complex task replete with risk.  Counsel submitted that the prejudicial effect of the coincidence evidence — the very significant risk of the jury misusing and overvaluing the evidence in their assessment of charges 1, 2 and 3, even after carefully formulated directions — is high.  Notwithstanding careful directions, the risk of misuse of the evidence will be incurable.  The prejudicial effect of the evidence will outweigh any probative value it may have.
Discussion
186	Any analysis of the admissibility of coincidence evidence in this case must start with the key provisions of the Act.
187	By s 55(1), ‘evidence that is relevant in a proceeding is evidence that, if it were accepted, could rationally affect (directly or indirectly) the assessment of the probability of the existence of a fact in issue in the proceeding’.  Section 56(1) makes clear that, save as otherwise provided by the Act, evidence that is relevant in a proceeding is admissible; and by s 56(2), evidence that is not relevant is not admissible.
188	The expression ‘fact in issue’, found in s 55(1), is not defined in the Act.  It is clear, however, that in a criminal case the ultimate issue will be the existence of one or more of the elements of an offence.  Facts in issue in the proceeding will be those bearing on the existence of those elements, and behind those will potentially be many facts relevant to those facts in issue.
189	Coincidence evidence is tendered to prove a particular fact (or facts) in issue: to show that a person did a particular act or had a particular state of mind.  Such evidence invites scrutiny of the similarities of events and the circumstances in which the events occurred, in order to show that it is improbable that they did not occur coincidentally.  Hence, so far as presently relevant, ss 98(1) and 101(2) of the Act provide:
98 	The coincidence rule
(1) 	Evidence that 2 or more events occurred is not admissible to prove that a person did a particular act or had a particular state of mind on the basis that, having regard to any similarities in the events or the circumstances in which they occurred, or any similarities in both the events and the circumstances in which they occurred, it is improbable that the events occurred coincidentally unless —
	…
(b)	the court thinks that the evidence will, either by itself or having regard to other evidence adduced or to be adduced by the party seeking to adduce the evidence, have significant probative value.
101	Further restrictions on tendency evidence and coincidence evidence adduced by prosecution
	…
(2)	Tendency evidence about an accused, or coincidence evidence about an accused, that is adduced by the prosecution cannot be used against the accused unless the probative value of the evidence substantially outweighs any prejudicial effect it may have on the accused.
190	The Dictionary to the Act defines the probative value of evidence as ‘the extent to which the evidence could rationally affect the assessment of the probability of the existence of a fact in issue’.  As s 98(1) by its terms makes clear, however, in order to be admissible it is not enough that coincidence evidence merely have probative value: the evidence must have significant probative value (either by itself or having regard to other evidence adduced or to be adduced by the party seeking to adduce the evidence).
191	Section 98(1) creates an exclusionary rule.  Coincidence evidence will be excluded unless the evidence reaches a high threshold of admissibility.  That this is so is emphasised by s 101(2) of the Act, which provides that in criminal cases, coincidence evidence adduced by the prosecution cannot be used against him or her ‘unless the probative value substantially outweighs any prejudicial effect it may have’.  When read together, the provisions of ss 98(1) and s 101(2) make it abundantly clear that coincidence evidence must possess a high degree of cogency before it will be admitted.
192	In the course of oral argument, the Court sought to have counsel for the applicant identify with precision the fact (or facts) in issue that the prosecution wanted to adduce the purported coincidence evidence to prove.  Hence, when a member of the Court asked senior counsel for the applicant to identify the fact or facts in issue relating to the first three charges that the prosecution sought to prove from the evidence ‘with respect to the four poisonings at the lunch’, senior counsel’s reply — to me, a non sequitur — was: ‘To negate the reasonable possibility that it was an accidental poisoning of the four lunch guests’.  (As I have noted, counsel for the applicant in written contentions submitted that the prosecution seeks to utilise coincidence reasoning in two distinct, but related ways: first, the prosecution seeks to adduce evidence of Events 1 to 3 to negate any reasonable possibility of Event 4 being an accidental poisoning; and, secondly, to utilise evidence of Event 4 to prove that Events 1, 2 and 3 were also poisonings.)
193	Further, when a member of the Court posed to senior counsel for the applicant the question, ‘Where we don’t know what caused Mr Patterson’s illnesses on those three occasions [founding charges 1, 2 and 3], isn’t it purely speculative to use the poisoning at the lunch to prove that [the respondent] poisoned him on those three occasions?’, counsel responded:
	No, with respect, that’s incorrect.  Coincidence reasoning – with the similarities that the Crown has identified between the Events, and circumstances in which they took place, we say that they – it’s an improbability that these charges [sic] 1, 2 and 3 occurred by coincidence.  It doesn’t matter about whether the Crown can nominate which poison it was if any for those three ---.
194	When it was pointed out that if it is if any — that is, the prosecution could not show that poison was used on those three occasions — then the purported coincidence evidence had no probative value; and after another member of the Court made the observation — with respect, one with which I cannot agree — that, ‘It may in the context of other evidence’; senior counsel responded, ‘Yes.  I’m simply trying to be fair’.  And counsel submitted:
	So what we say is, if you take into account all of the similarities, across all of the four Events, then it is improbable as a coincidence that Event 4 was an accidental poisoning, and then it works the other way.  We say that, similarly, one can use the coincidence evidence, in a short-hand way, the improbability of coincidence, that the Events 1, 2 and 3 were poisonings [sic].
195	Moreover, when then asked to identify the fact in issue in relation to Event 4 — ‘the three alleged murders and attempted murder relating to the lunch’ — that the prosecution seeks to prove by the coincidence evidence of Events 1, 2 and 3, senior counsel for the applicant responded:
	That the Event 4 was not an accidental – sorry, there’s not a reasonable possibility that the poisoning that occurred at Event 4 was accidental.  That’s how we seek to use 1, 2 and 3 and coincidence evidence.
196	I have set out the exchanges above in a little more detail than is customary, since, to my mind, they starkly demonstrate the fallacious logic underpinning the prosecution’s stance.  From the above it appears that, if permitted to do so, the prosecution seeks to use the coincidence evidence in two ways.  First, the prosecution wants to use the fact that Simon Patterson became seriously ill on three occasions after eating food prepared by the respondent (Events 1, 2 and 3) in proof that the lunch poisonings (Event 4) were not accidental.  And then, according to the prosecution, ‘it works the other way’, so that, secondly, the prosecution wants to use the fact that the four lunch guests were poisoned in proof of the fact that the respondent deliberately poisoned Simon Patterson on three occasions when she gave him food she had prepared (and he subsequently became ill).
197	As earlier discussed, Professor Andrew Bersten examined Simon Patterson’s medical files in order to determine whether a ‘unifying diagnosis’ could be made of his illnesses relevant to charges 1, 2 and 3 (Events 1, 2 and 3).  With respect to the first illness in November 2021, Professor Bersten was of the view that it was likely that there was either a toxic or an infective cause (although, if it was caused by the ingestion of a toxic substance, Professor Bersten could not suggest what that substance could be).  Professor Bersten was uncertain of the cause of the second illness, albeit that it was likely there was a toxic or an infective cause.  As to the third illness, Professor Bersten considered that Simon Patterson’s heart rhythm disturbance was related to extremely low blood potassium, but that any interpretation of this illness is complicated by the bowel resection carried out during the second illness.  Importantly, Professor Bersten expressed the view with respect to the first and second illnesses that the lack of damage to Mr Patterson’s liver was inconsistent with poisoning by death cap mushrooms.
198	To risk repetition, several things may be drawn from Professor Bersten’s evidence: first, Simon Patterson’s gastrointestinal symptoms on each occasion were severe and sudden in onset; secondly, despite reasonably extensive investigation and testing, the cause (or causes) of Mr Patterson’s gastric disturbance could not be identified; thirdly, it was possible that the three illnesses could have resulted either from infection or the ingestion of poison (a chronic bowel condition being unlikely); fourthly, assuming either an infective cause or toxic cause, neither an infective source nor a poison was identified; and, fifthly, the lack of liver damage suffered by Mr Patterson was inconsistent with poisoning by death cap mushrooms.
199	It is important to note that the prosecution case is that part of the respondent’s modus operandi for the lunch poisonings, Event 4, was to employ death cap mushrooms as a poisonous substance, but that she had a different modus operandi when it came to poisoning her husband, Events 1, 2 and 3, at least to the extent that she did not use death cap mushrooms as a poison (albeit that the prosecution would have it that there was a similar modus operandi in other respects).  Hence, in oral argument, senior counsel for the applicant submitted:
	Events 1 to 3, there is no evidence that mushrooms were involved. … There was no known cause of what caused Simon Patterson to fall ill as he did for Events 1, 2 and 3. … It’s not the prosecution case that Simon Patterson was poisoned with death cap mushrooms for Events 1, 2 or 3. … But the Crown has never alleged, and does not allege, that death cap mushroom was put into the meals for those three Events [Events 1, 2 and 3].
200	Taken alone, the medical evidence cannot support the inference that Simon Patterson was poisoned by anybody on the three occasions upon which he became ill, let alone that it was the respondent who poisoned him.  According to Professor Bersten, Mr Patterson’s gastrointestinal disturbance could have resulted from an infective cause, including from a viral infection of the intestinal tract or from toxins produced through bacterial infection.  The fact that testing did not detect an infective cause does not establish that one did not exist.  Accepting that the gastrointestinal disturbance could have been the result of ingesting a toxin, Professor Bersten could not suggest what that toxin might have been.  Since Mr Patterson did not suffer the kind of liver damage usually associated with death cap mushrooms, however, it seems unlikely that they were the source of his illnesses.  Of significance, Professor Bersten’s evidence was that the mere fact that a person developed gastrointestinal symptoms after eating a meal did not necessarily mean that the meal was responsible.
201	Given the inability of the medical evidence alone to establish that Simon Patterson’s illnesses were as a result of poisoning — let alone that the respondent was his poisoner — the following exchange in oral argument between a member of the Court and senior counsel for the applicant sheds light on the dubious way in which the prosecution seeks to put its case:
	[JUDGE]  So, you say that, the similarities that you rely upon show that when she provided meals in a certain way and to certain people, those people became very sick, very quickly, to the point of death.  That’s the first part of your argument.
	[COUNSEL:]  Yes.
	[JUDGE:]  And you say that leads to the ultimate inference in all eight cases of poisoning and all four Events that this is too much of a coincidence for this to be spontaneous gastric illness and too much of a coincidence to be an unfortunate culinary accident.
	[COUNSEL:]  Yes, that’s so.
	[JUDGE:]  And that’s how you put your case.
	[COUNSEL:]  That’s how we put our case.
	[JUDGE:]  OK.
	[COUNSEL:]  Although the first bit about similarities they are particular similarities rather than generalised similarities if I could put it that way.
202	From the exchange immediately above, it is clear that senior counsel for the applicant embraced the formulation of the prosecution case that, when the respondent provided meals ‘in a certain way’ and ‘to certain people’, those people very quickly became very sick, leading to the ultimate inference ‘in all eight cases of poisoning’ and ‘all four Events’ that it is too much of a coincidence for this to be either ‘spontaneous gastric illness’, or, alternatively, ‘an unfortunate culinary accident’.
203	A very troubling aspect of this formulation of the prosecution case is, however, that it is attended with the same circular reasoning that led the trial judge to exclude the coincidence evidence and to sever the indictment.  Indeed, it proceeds on the assumption that there were eight cases of poisoning, in circumstances where the central fact in issue on charges 1, 2 and 3 is whether the respondent in fact poisoned her husband (in circumstances where the medical evidence cannot exclude another possible cause of Simon Patterson’s three illnesses).
204	In my opinion it is clear that the prosecution case relies on the same kind of circular reasoning that was deprecated by the High Court in Perry.
205	Perry was a poisoning case involving the admissibility of similar fact evidence at common law.  Bearing in mind that it was not, as is this case, concerned with the provisions of the Act — so that care must be taken in applying it in the present situation — much of the reasoning of the members of the High Court is compelling.  Indeed, some of the language used appears to anticipate the provisions of the Act.
206	Emily Perry faced trial on two charges of the attempted murder of her third husband, Kenneth Perry, who was found to be suffering from arsenic poisoning.  The trial judge admitted evidence tendered by the prosecution that her second husband, Albert Haag, and her brother, Francis Montgomerie, had died of acute arsenic poisoning in 1961 and 1962 respectively, and that her de facto husband, Jim Duncan, died from an overdose of barbiturates in 1970.  There was clear evidence that during part of the periods in question in 1978 and 1979, the applicant’s husband, Mr Perry, became seriously ill as a result of poisoning by lead and arsenic.  The applicant, who was living with Mr Perry, had the opportunity to administer the poison to him, and she stood to benefit financially from his death by way of insurance policies.  The ‘defence’ was that the poison had been accidentally ingested by Mr Perry over a period of time and that the applicant had not played any part in causing him to take it.  Mrs Perry was convicted at trial, and a subsequent appeal to the Court of Criminal Appeal (SA) failed.  She sought special leave to appeal from the High Court.  The High Court granted special leave; allowed the appeal; and ordered a new trial.
207	There was evidence at the trial that Haag died on 13 March 1961 of acute arsenic poisoning.  He had previously been ill in December 1960 and January 1961, and there was evidence that this illness might have been due to arsenical poisoning.  The applicant stood to benefit from insurance policies on his life.
208	Montgomerie died on 9 April 1962, also from acute arsenical poisoning.  He was an alcoholic, given to moodiness and depression, and he had twice been admitted to a psychiatric hospital.  On the evidence, the applicant may have been the last person to see Montgomerie alive, and the first to find him dead.  Bottles were found on a bedside table, including a bottle containing a small quantity of wine and some arsenic.  A post mortem examination showed arsenic in the body.  There was evidence that one of the applicant’s sisters had bought some weed killer a few days previously, that had been placed by the applicant on a shelf at her mother’s house.  It was said that this showed that the applicant had access to the poison.  The defence argued that the circumstances pointed clearly to suicide.
209	Duncan, who commenced living with the applicant at the end of 1967, died on 21 March 1970 from an overdose of barbiturates.  Insurance policies on his life had been arranged by the applicant during 1968 and she received payment under them after his death.  Duncan had swallowed about twenty tablets of barbiturates.  It was most unlikely that the applicant could have forced him to swallow them.  In circumstances resonant of the present case, the prosecution relied on evidence which, it submitted, showed that Duncan had suffered from arsenical poisoning over a considerable period before his death.  Duncan had operations for haemorrhoids in 1944 and 1957, and, by the beginning of 1968, was seeking medical treatment for anal trouble (and underwent another operation for haemorrhoids that year).  From the end of 1968, he was complaining of some loss of bowel control and pains in the lower abdomen; and, by the end of 1969 and the beginning of 1970, of diarrhoea, incontinence, vomiting, pain, and other symptoms.  None of the many doctors who examined him diagnosed heavy metal poisoning, and no test was made, prior to his death or post-mortem, for the presence of arsenic.  An expert medical witness for the prosecution said that Duncan’s symptoms were consistent with, but not specific for, the ingestion of lead arsenate.  When he conducted an autopsy on Duncan’s body, however, he saw no signs of heavy metal poisoning.
210	In the High Court, Gibbs CJ discussed the admissibility of similar fact evidence at common law, and said
	it is not right to treat evidence which tends to show the commission by the accused of other criminal acts in the same way as any other circumstantial evidence.  In the first place, as I have already said, a jury might place too much weight on the fact that the accused had a criminal tendency.  Secondly, evidence of this kind will often raise difficult and doubtful questions as to whether the accused had in fact been guilty of other criminal acts, and may distract the attention of the jury from the vital issues in the case.  It is therefore not enough that the evidence should be only technically relevant (otherwise than as showing a propensity); it must be really material; it must have strong probative force.
211	Later, Gibbs CJ said:
	that evidence tendered to prove the similar fact which it is sought to admit in accordance with these principles must have a strong degree of probative force.  It is not enough that it merely raises a suspicion that the accused may have been guilty of the similar misconduct alleged or of the crime charged.
212	As to the path of reasoning in a poisoning case, Gibbs CJ observed:
	Clearly on principle it is not admissible, on a charge of murder or attempted murder by poisoning, to give evidence that the accused has poisoned other persons, where that evidence shows no more than that the accused is a poisoner – one who has a tendency to poison others.  However, where a number of poisonings have occurred, and the victims have all been associated with the accused person, the evidence of the other poisonings may be admissible to support the inference that the accused was responsible for the death in issue, because it would be contrary to ordinary experience that a series of poisonings, caused by accident or suicide, would occur by coincidence in the circle of persons with whom the accused was associated.  In such cases, the evidence is admissible for reasons similar to those which governed the admissibility of the evidence in Makin v Attorney-General (NSW)[] and R v Smith[] …
213	Although he was of the view that the evidence relating to Haag was admissible, Gibbs CJ held that the similar fact evidence in relation to Duncan and Montgomerie was inadmissible.  Of the evidence relating to Duncan, he said:
	It was not established that Duncan had ingested any poison (except of course the barbiturates, with whose consumption the applicant was not shown to have had anything to do).  It was necessary for the Crown to rely on the other instances of poisoning, including those the subject of the present charges, in an attempt to provide a basis for an inference that Duncan had suffered from arsenical poisoning.  In other words, it was necessary to assume the guilt of the applicant of the offences of which she was charged in order to render admissible the evidence regarding the death of Duncan.  Such a line of reasoning is obviously objectionable.
214	And in relation to the evidence concerning Montgomerie, Gibbs CJ said:
	The evidence linking the applicant with the death of Montgomerie does no more than raise a suspicion that she poisoned him, and viewed alone it would hardly even raise a suspicion.  There is no striking similarity between the circumstances of the death of Montgomerie and those of the poisoning of Mr Perry.  On the whole it seems to me that the evidence relating to Montgomerie is not sufficiently cogent to be admitted.
215	Murphy J considered that none of the supposed similar fact evidence concerning Duncan, Montgomerie or Haag was admissible.  He observed:
	In Mrs Perry’s case there is a very great temptation in weighing the evidence and more particularly in deciding admissibility, to ignore the presumption of innocence and to replace it with a presumption of guilt.  The allegation that a number of the accused’s relatives died or suffered from arsenic poisoning immediately conjures up a highly suspicious prejudicial atmosphere in which the presumption of innocence tends to be replaced with a presumption of guilt.  The presumption of innocence and the strict standard of proof required in criminal cases tend to be indirectly and subtly undermined from the outset by reference to a sequence of events which according to common human experience would not occur unless the accused were guilty.
216	Moreover, Murphy J was of the view that the impugned evidence was attended by circular reasoning.  He said:
	There is a danger of admitting and using evidence of collateral circumstances (the death of Haag, or of Montgomerie, or the sickness of Duncan) which not only standing alone, but taken together with the other evidence (including any which independently tends to establish the central issue), is insufficient to exclude a rational explanation of that circumstance consistent with the accused’s innocence, and then using the supposed guilt in relation to that circumstance as proof of others and the central issue.  For example, on the prosecution’s theory the supposed poisoning of Duncan depended on acceptance that Haag, Montgomerie and Perry were poisoned by the applicant, but the proof of these poisonings depended on the acceptance that she poisoned Duncan. … Evidence of any circumstance such as any of the alleged poisonings of Duncan, Haag or Montgomerie should be discarded when it appears on consideration of the whole of the evidence that there is reasonable doubt about the accused’s culpability in relation to that circumstance.  Otherwise the stage is being set for a miscarriage of justice.
217	Wilson J considered that the similar fact evidence relating to Haag was admissible, but that the evidence relating to Montgomerie was ‘borderline’ (albeit that he was not prepared to hold that the evidence relating to Montgomerie was inadmissible).  The evidence relating to Duncan, however, should not have been admitted.
218	Finally, Brennan J was of the opinion that the evidence concerning Duncan should not have been admitted.  The evidence relating to Montgomerie and Haag, however, had sufficient probative force to warrant its admission.  Brennan J said:
	But no inference that Mr Duncan had ingested arsenic could safely be drawn from the facts  proved.  The symptoms he exhibited might well have been due to other causes.  The suspicion that his symptoms were caused by arsenical poisoning arises in part – as the Crown conceded – from the fact that Mr Perry suffered from chronic arsenical poisoning.  But the mere ingestion of arsenic by Mr Perry could throw no light upon the cause of Duncan’s symptoms unless it be assumed that the arsenic ingested by Mr Perry had been administered to him by Mrs Perry.  That assumption cannot be made; administration of arsenic by Mrs Perry is the fact in issue which the evidence relating to Duncan’s symptoms is tendered to prove.  To seek to prove a fact in issue by a chain of reasoning which assumes the truth of that fact is, of course, a fallacy, repugnant alike to logic and to the practical processes of criminal courts.  Nor is the evidence relating to the deaths of Haag and Montgomerie sufficient to found an inference that Duncan’s symptoms were caused by ingesting arsenic.  The poisoning of a number of persons in a family circle may be admissible to aid in proving that all were the victims of a common poisoner, but that is not to say that the same evidence will prove the poisoning of another member of the family the aetiology of whose symptoms is unknown.  There was no evidence upon which the jury could have been satisfied that Duncan’s symptoms were caused by ingesting arsenic.  As the evidence relating to Duncan falls short of establishing that his was another case of arsenical poisoning, that evidence was not probative of a fact in issue and it ought to have been excluded as irrelevant.  As it was admitted and treated as probative of guilt, the trial miscarried.
219	All members of the High Court were of the view that the supposed similar fact evidence in the case of Duncan should not have been admitted.  It will be remembered that Duncan, who commenced living with Mrs Perry at the end of 1967, died in March 1970 from an overdose of barbiturate tablets.  At trial, the prosecution relied on evidence which it claimed showed that Duncan had suffered from arsenical poisoning over a considerable period before his death.  That evidence included that, from the end of 1968 he was complaining of some loss of bowel control and pains in the lower abdomen; and, by the end of 1969 and the beginning of 1970, of diarrhoea, incontinence, vomiting, pain, and other symptoms.  Importantly, none of the many doctors who examined him diagnosed heavy metal poisoning, and no test was done, prior to his death or post-mortem, for the presence of arsenic.  And although an expert medical witness called by the prosecution said that Duncan’s symptoms were consistent with the ingestion of lead arsenate, they were not specific for arsenic poisoning.  An autopsy conducted on Duncan’s body, however, showed no signs of heavy metal poisoning.
220	There are a number of relevant comparisons that may be made between the evidence relating to Duncan’s situation in Perry and that relating to Simon Patterson in this case.  In the same way that Duncan suffered from diarrhoea, incontinence, vomiting, pain, and other symptoms over a couple years, in circumstances where Mrs Perry had the opportunity in the course of cohabiting with him to administer poison to him, Simon Patterson suffered from gastrointestinal disturbance on at least three occasions between November 2021 and September 2022, in circumstances where the respondent had the opportunity to administer poison to him.  Unlike Duncan’s situation, however, the prosecution have suggested a mechanism by which they claim the respondent administered poison to her husband.  Hence, the allegation is that the respondent gave Mr Patterson poison in food that she prepared, albeit that there is no direct evidence — medical or otherwise — that the meals contained poison (let alone the nature of the poison).
221	Further, the prosecution in Perry asserted that Duncan had been poisoned with lead arsenate.  That is despite the fact that, although some of his symptoms were consistent with that kind of poisoning, they were also consistent with other possible causes.  No doctor who examined Duncan ever diagnosed heavy metal poisoning, and, significantly, an autopsy did not reveal any evidence that he had been poisoned with arsenic.  In much the same way, the medical evidence in the present case suggests that Simon Patterson’s gastrointestinal disturbance could have been the result of an infective cause, or the result of ingesting a poison (or the result of some other cause).  Despite moderately extensive testing, however, no cause was found for his disturbance.  Certainly, no possible poison was identified in medical testing.  And beyond asserting that it is not part of the prosecution case that Mr Patterson was poisoned with death cap mushrooms, the prosecution has identified no poison as the possible culprit.
222	In Perry, the fact in issue that the supposed similar fact evidence relating to Duncan was tendered to prove was that Mrs Perry had deliberately administered poison to her husband.  By way of contrast, there is no dispute in this case that the respondent’s four lunch guests on 29 July 2023 were in fact poisoned — with death cap mushrooms — the fact in issue being whether the poisoning was deliberate or accidental.  As I have said, the prosecution seeks to prove that disputed fact in issue by adducing evidence that Simon Patterson became seriously ill on three occasions after eating food prepared by the respondent.
223	Drawing on the reasoning in Perry, I am, as I have indicated, of the view that the judge was correct to rule that the purported coincidence evidence sought to be relied upon by the prosecution is inadmissible.
224	It cannot be gainsaid that the undisputed fact that the respondent actually served her lunch guests poisoned food (Event 4) will raise a suspicion in the minds of jurors that she also gave her husband poisoned meals (Events 1, 2 and 3).  Indeed, in any trial on the indictment as presently formulated, the fact that a number of people related to her husband became seriously ill on a particular occasion after eating admittedly poisoned food that the respondent served them will conjure up a highly suspicious, prejudicial atmosphere, in which the presumption of innocence will tend to be obscured in the minds of any jury.
225	Importantly, however, I consider that an inference that Simon Patterson ingested poison — whether at the hands of his wife or by other means — could not safely be drawn on the available evidence.  According to the medical evidence, the gastrointestinal symptoms he exhibited may well have been due to other causes.  The suspicion that his symptoms were caused by poisoning, however, arises in substantial part from the fact that the respondent’s lunch guests suffered from death cap mushroom poisoning, and will likely overwhelm a jury’s objective consideration of charges 1, 2 and 3.
226	Logically, the mere ingestion of poison by the respondent’s lunch guests throws no light upon the cause of Simon Patterson’s gastrointestinal disturbance unless it be assumed that the respondent also served him poisoned food.  As a matter of principle, however, that assumption cannot be made.  To seek to prove that fact in issue by a chain of reasoning which assumes the truth of the fact is fallacious, and offensive both to logic and to the burden and standard of proof in a criminal trial.  In my opinion, the evidence relating to the deaths and illnesses of the respondent’s lunch guests is insufficient to found an inference that Mr Patterson’s symptoms were caused by ingesting poison.  The fact that certain people in the respondent’s family circle fell victim to poison in food that she served, is no proof that she poisoned another member of the family, her husband, in circumstances where the aetiology of his symptoms dwells in the realm of speculation.
227	In my opinion, the purported coincidence evidence of Event 4 is inadmissible in proof of charges 1, 2 and 3.  There is no evidence upon which a jury could properly infer that Simon Patterson’s symptoms were caused by ingesting poison.  As the evidence relating to the poisoning of the lunch guests cannot properly go in proof of the fact that Mr Patterson’s was another case of poisoning (deliberate or otherwise), that evidence is not probative of any fact in issue and must therefore be excluded.
228	If I am wrong about that, however, and the evidence relating to the poisoning of the respondent’s lunch guests possesses some probative value on the charges that allege that she attempted to murder her husband by poisoning (charges 1, 2 and 3), any probative value that the evidence possesses — either by itself or in conjunction with other anticipated evidences — is not significant, and does not substantially outweigh any prejudicial effect it may have on the respondent.
229	As to that, I note that the Act does not define ‘significant’.  There have, however, been judicial attempts to ascribe a meaning to it.  Thus, the view has been expressed that the primary meaning of significant is ‘important’ or ‘of consequence’, and that ‘significant probative value’ must mean something more than mere relevance, but something less than a ‘substantial’ degree of relevance.  When dealing with the same requirement of significant probative value for tendency evidence under s 97(1)(b) of the Act, French CJ, Kiefel, Bell and Keane JJ observed in IMM:
	Cross on Evidence suggests that a ‘significant’ probative value is a probative value which is ‘important’ or ‘of consequence.  The significance of the probative value of the tendency evidence under s 97(1)(b) must depend on the nature of the facts in issue to which the evidence is relevant and the significance or importance which that evidence may have in establishing those facts.  So understood, the evidence must be influential in the context of fact-finding.
230	In both written and oral submissions, counsel for the applicant spent some time concentrating on the minutiae of the ‘similarities’ contended for in the notice, criticising the judge for the manner in which he dealt with them.  When they are distilled, however, I consider that the purported similarities establish no more than the respondent, in the course of social events that she had arranged, gave food that she had prepared to people to whom she was related by marriage, those people subsequently suffering severe gastrointestinal illness.  (It also appears that the respondent did not eat from precisely the same dishes that she served to others, and that her children were not present when the meals were consumed.)  To my mind, these supposed similarities are wholly unremarkable, and do not imbue the evidence with significant probative value.  Even if the fact that her lunch guests were poisoned were capable of going some way towards founding an inference that the respondent’s husband was also poisoned, in circumstances where the source of Simon Patterson’s gastrointestinal disturbance is empirically undeterminable, any such inference would be weak.
231	On the other hand, the prejudice flowing to the respondent from the reception of such evidence would be substantial.  As I have indicated, evidence that her lunch guests were poisoned will generate a high level of suspicion, and attract a great deal of prejudice, in which the presumption of innocence will struggle for recognition in the minds of any jury.  The prejudice engendered will not readily be amenable to adequate amelioration by judicial direction.
232	I also consider that the evidence of Events 1, 2 and 3 is inadmissible as coincidence evidence in proof of the fact that Donald Patterson, Gail Patterson, Ian Wilkinson and Heather Wilkinson were deliberately poisoned.  Since the cause of Simon Patterson’s gastrointestinal disturbance is indeterminable, and the fact that he fell ill after consuming food prepared by the respondent is no proof that he was poisoned, the facts founding charges 1, 2 and 3 cannot properly be considered coincidence evidence capable of going in proof of charges 4, 5, 6 and 7.  In my view, in order to use the events founding charges 1, 2 and 3 in proof of the disputed fact on charges 4, 5, 6 and 7, it must first be assumed that the respondent deliberately poisoned Simon Patterson.  But in circumstances where the cause of his gastrointestinal disturbance cannot be determined, to endeavour to use the evidence in that way would be fallacious.  It would involve circular reasoning, permitting impermissible speculation to displace legitimate inference.  Plainly, in my view, the evidence does not have significant probative value, substantially outweighing any prejudicial effect it would have on the respondent.
233	Finally, I note that counsel for the respondent did not submit that the charges on the indictment were improperly joined.  The defence position was that the interests of justice required severance of the indictment.  As to that, if an indictment contains more than one charge, s 193(1) of the CPA permits the court to order that any one or more of the charges be tried separately.  By virtue of s 193(3), an order that one or more charges on the indictment be tried separately may be made if the court considers that ‘the case of an accused may be prejudiced because the accused is charged with more than one offence in the same indictment’, or ‘for any other reason it is appropriate to do so’.
234	In TJB it was said that the forerunner of s 193, s 372(3) of the Crimes Act 1958 — which is in similar (though not identical) terms — conferred a ‘true discretion’.  Although TJB was a case of sexual offending involving three complainants, several principles laid down in that case to guide the exercise of discretion are of general application, four of which are particularly apposite.  Those principles are:
1	A presentment should always be severed where that is both desirable and practicable in order to ensure a fair trial.  It is for defence counsel to persuade the judge that that is so.  In that respect sexual offences are no different from other offences.
2	One aspect of a fair trial is the taking of reasonable steps to prevent a jury from misusing evidence.  That is not limited to propensity evidence and again is not peculiar to trials of sexual offences.  See, for example, R v Smart [[1983] 1 VR 265] especially at 283 and 289.
3	It is usually to be assumed that the jury will comply with any directions they are given by the judge.  A fair-minded lay observer takes that very factor into account in considering whether a trial is fair: cf. Webb v R (1994) 181 CLR 41 at 55.
4	There are nevertheless cases where the risk of prejudice is unacceptable.  It will often be found that that is so in the case of offences of an unnatural character or offences that arouse strong emotions or excite revulsion.
5.	[Not reproduced.]
235	In considering whether the prejudice flowing to an accused person from the failure to sever a charge or charges may be unacceptable, a key consideration for a trial judge is whether the anticipated prejudice is amenable to adequate amelioration or elimination by judicial direction.  Although the system of criminal trial by jury must proceed on the supposition that jurors will follow the directions that are given to them, the law also recognises that there will be situations in which the elimination or adequate reduction of prejudice by judicial direction will be practically impossible.  In my view, this is such a case.  The suspicion and prejudice engendered by the evidence concerning Event 4 will very likely insidiously permeate the jury’s consideration of charges 1, 2 and 3, in a manner that will not be capable of adequate amelioration by direction.  Similarly, the suspicion and prejudice engendered by the evidence concerning Events 1, 2 and 3 will very likely pervade the jury’s consideration of charges 4, 5, 6 and 7, in a manner that will not be capable of being effectively remedied by direction.  As the trial judge recognised, severance of the indictment was required to prevent an unfair trial.
236	For these reasons, the judge’s ruling was correct.  None of the grounds has substance.
237	Leave to appeal must be refused.
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