EP#159 | How Expert Evidence Contributes to Wrongful Convictions

Expert evidence, particularly in cases of trauma and abuse, can be misused to wrongly validate witness testimony, potentially leading to wrongful convictions if not properly scrutinized

Questions to inspire discussion

Expert Evidence Admissibility

🧪 Q: What is the Mohan test for expert evidence admissibility?
A: The Mohan test requires expert evidence to be logically relevant, necessary to assist the trier of fact, not exclusionary, and from a properly qualified expert with special knowledge beyond the trier of fact's expertise.

🔬 Q: How does the White Burgess Longville decision impact expert evidence admissibility?
A: It requires a cost-benefit analysis balancing the probative value of expert evidence against its prejudicial effect to determine admissibility in court proceedings.

Sexual Assault Cases and Expert Testimony

🧠 Q: Is expert evidence on neurobiology of trauma necessary in sexual assault cases?
A: Expert evidence on neurobiology of trauma is not required to explain typical behaviors like delayed reporting or avoidance, as these are no longer considered rape myths and judges can admonish juries against them.

👩⚖️ Q: What issues arose with expert testimony in the RV v. PJC 2025 case?
A: The expert was not properly qualified to testify on neurobiology of trauma, lacked objectivity, and testified on the ultimate issue of the complainant's credibility, which is impermissible.

Dangers of Expert Evidence

⚖️ Q: How can expert evidence be misused in sexual assault trials?
A: Expert evidence can be misused to bolster complainant credibility, blunt cross-examination, and usurp the judge's role in assessing credibility, potentially leading to wrongful convictions.

🚫 Q: What is the primary danger of admitting expert evidence?
A: The primary danger is that jurors may abdicate their role as fact finders and simply accept the expert's opinion, especially in judge-alone trials.

Hypothetical Questions and Expert Testimony

❓ Q: Why were the hypothetical questions in RV v. PJC 2025 problematic?
A: The hypotheticals referenced distinctive features of the complainant's evidence, which is impermissible as expert evidence should be generic and not specific to the case.

🔍 Q: How did the hypotheticals potentially influence the case outcome?
A: They essentially asked the expert to testify to the veracity of the complainants' evidence, cloaking it with scientific reliability and indirectly asking if the complainants were truthful.

Legal Implications and Future Considerations

🏛️ Q: How did the Supreme Court's Curative Proviso impact this case?
A: It limited how the expert's evidence could be used, as it went beyond providing context and usurped the judge's role in assessing credibility.

🚪 Q: What is the significance of the Court of Appeal's decision on neurobiology of trauma evidence?
A: It effectively shuts the door on using neurobiology of trauma as beneficial evidence in sexual assault cases, deeming it ripe for abuse.

Expert Evidence and Wrongful Convictions

⚠️ Q: Why is scrutiny of expert evidence crucial in preventing wrongful convictions?
A: Scrutiny is crucial because soft sciences like psychology are not as replicable as hard sciences and can lead to miscarriages of justice if not properly evaluated.

🔒 Q: What is the presumption regarding expert evidence admissibility?
A: Expert evidence is presumptively inadmissible and only allowed when the trier of fact is unable to form a correct judgment without expert help, providing unique special knowledge necessary for a just conclusion.

Key Insights

Legal Framework for Expert Evidence

1. 🧑⚖️  Apply the Mohan test to ensure expert evidence is logically relevant, necessary, not exclusionary, and properly qualified before admission in court.
2. 🔬 Distinguish between "hard sciences" (e.g., toxicology, blood alcohol testing) and "soft sciences" (e.g., psychology) when evaluating expert evidence admissibility.
3. ⚖️ Conduct a cost-benefit analysis balancing the probative value against prejudicial effect of expert evidence, as per White Burgess Longville v. Abbott and Haliburton Co. (2015 SCC 22).

Expert Evidence in Sexual Assault Cases

1. 🚫  Avoid using expert evidence on neurobiology of trauma to explain typical rape myths, as these are no longer considered myths and judges can admonish juries against them.
2. 🎯 Ensure expert witnesses are properly qualified to testify on specific topics and have individually assessed the complainant to provide objective evidence.
3. 📊 Use generic expert evidence rather than case-specific testimony to prevent prejudice and ensure a fair trial.

Potential Misuse of Expert Evidence

1. 🚨  Be vigilant against expert evidence being used to bolster complainant credibility, blunt cross-examination, or usurp the judge's role in assessing credibility.
2. 🧠  Recognize that jurors may abdicate their fact-finding role and simply accept expert opinions, especially in judge-alone trials.
3. 🔍 Scrutinize hypothetical questions posed to experts to ensure they don't indirectly ask about the veracity of complainants' evidence.

Recent Legal Developments

1. 📜 Apply the Supreme Court's Curative Proviso to limit how expert evidence can be used when it goes beyond providing context and usurps the judge's role.
2. 🚪 Note that the Ontario Court of Appeal's decision effectively closes the door on using neurobiology of trauma as beneficial evidence in sexual assault cases.
3. 🔒  Presume expert evidence is inadmissible unless it provides unique special knowledge necessary for a just conclusion that the trier of fact cannot form without expert help.

#Justice

XMentions: @HabitatsDigital @NotOnRecord @NeubergerLaw @d2davison

Clips

• 00:00 💡 Expert evidence, particularly in cases of trauma and abuse, can be misused to wrongly validate witness testimony, leading to potential wrongful convictions.
  • The podcasters discuss a recent Ontario Court of Appeal case, highlighting their long-standing concern about junk science and expert evidence, particularly a psychologist's testimony on the neurobiology of trauma being used to validate abuse allegations.
  • Expert evidence is being used to transform inconsistencies and memory gaps in witness testimony, typically seen as reasons to doubt a conviction, into signs of credibility, particularly in rape cases, by attributing them to trauma experienced by the victim.
  • The issue with expert evidence lies in its potential to be misplaced, misleading, and prejudicial to a fair trial, particularly when used by certain experts testifying on behalf of the crown.
  • The speaker commends a well-structured document on expert evidence, suggesting it's easily understandable even for non-experts, and offers to explain the basics of expert evidence and its admissibility parameters.
  • Expert evidence in trials must meet four conditions to be admissible: logical relevance to a material issue, necessity to assist the trier of fact, and dealing with subject matter beyond ordinary people's understanding.
  • Expert opinion evidence is presumptively inadmissible and requires a two-part test, including a cost-benefit analysis balancing probative value against prejudicial effect, to be admitted in court.
• 06:37 💡 Expert evidence, especially from subjective fields like psychology, can contribute to wrongful convictions if not properly scrutinized, highlighting the need for courts to remain vigilant.
  • Courts now accept that experts aren't required to testify that real victims of sexual assault may not report immediately or exhibit avoidant behavior, as these concepts are generally understood and no longer considered "rape myths".
  • Discriminatory beliefs in the system, based on outdated understandings of victim behavior, have been addressed through case law and should not require expert evidence.
  • Expert evidence can lead to wrongful convictions if not properly scrutinized, as seen in cases like that of Dr. Smith, a pediatric pathologist who fabricated evidence, highlighting the need for courts to remain vigilant in admitting expert evidence.
  • Expert evidence from "hard sciences" like toxicology and DNA can be replicated and verified, whereas "soft sciences" like psychology, which involve interpreting thoughts and feelings, are more subjective and prone to variability.
  • An expert witness testified about a case without directly assessing the complainant, instead relying on pre-trial testimony and general assumptions about victim behavior.
• 12:46 💡 Expert evidence, particularly in cases of childhood trauma, can contribute to wrongful convictions by providing skewed findings that unduly influence the court.
  • An expert psychologist's testimony on the neurobiology of trauma and its effects on memory must be objective and not based on individual assessment of the complainant, lest it compromise the credibility of the case.
  • Expert evidence on the neurobiology of trauma, specifically the encoding, storage, and retrieval of memories, can be confusing and unhelpful to judges and juries, particularly in cases of childhood sexual assault.
  • Expert evidence, such as psychologist reports, can bolster child complainant testimony, but raises questions about whether it unduly influences the court and if judges require education on child testimony.
  • A child's failure to remember a detail like ejaculation during an investigation is not necessarily significant, as they may not have understood the concept in the first place.
  • Expert evidence can contribute to wrongful convictions by providing skewed findings, such as using dissociative amnesia to explain away memory gaps that raise reasonable doubt.
  • In a trial, expert evidence must be deemed admissible through a pre-trial hearing, called a "Voir Dire", where the defense can challenge the expert's testimony to ensure they don't opine on the ultimate question of the case, but can still argue its weight later on.
• 20:16 💼 Expert evidence can contribute to wrongful convictions when experts' testimonies are influenced by complainants' evidence or when they bolster the complainant's credibility, leading to potentially misleading and unreliable evidence.
  • In a court case, the crown presented hypothetical scenarios to an expert that subtly incorporated details of the complainant's evidence, potentially influencing the expert's testimony and contributing to a wrongful conviction.
  • The order of expert testimony can be crucial in trials, as experts should testify before complainants to avoid their opinions being influenced by previously heard evidence.
  • A child who is repeatedly assaulted over a period of time will not be able to provide an exact sequence of events or timeframe when the events took place as an adult.
  • Expert witnesses who interview complainants and then testify on their credibility can compromise objectivity and bolster the complainant's credibility, leading to potentially misleading and unreliable evidence.
  • The expert considers the statements made to be consistent with how individuals who have experienced dissociative episodes, such as those in childhood or historical sexual abuse cases, describe their experiences.
  • The trial judge ruled that the expert's evidence on the neurobiology of trauma was admissible as it provided a necessary explanation for the inconsistencies in the complainants' evidence, which was outside the knowledge of a typical Canadian person.
• 26:12 💡 Expert evidence can contribute to wrongful convictions by improperly bolstering complainant credibility and limiting cross-examination, even if initially deemed necessary.
  • The prosecutor used expert evidence to bolster the complainant's credibility, effectively "oath helping", despite the judge noting it was only one factor to consider, leading to a potentially wrongful conviction.
  • Expert evidence can contribute to wrongful convictions by improperly bolstering complainant credibility and limiting cross-examination, even if the evidence was initially deemed necessary.
  • Even if a judge admits expert evidence, defense counsel can still cross-examine on its limitations and make submissions on its use, and the judge must carefully assess how the evidence can be used.
  • Expert evidence can be misplaced in trials as jurors may overly rely on an expert's credentials and opinion, potentially abdicating their role as fact-finders.
  • Expert evidence should be excluded if it improperly bolsters a complainant's credibility, has a prejudicial effect that outweighs its probative value, or fails to meet the necessity requirement for admission.
  • The Crown's ability to bring in expert witnesses at the state's expense, while requiring the accused to personally pay for counter-experts, can lead to wrongful convictions.
• 33:47 💡 Expert evidence, especially in sexual assault cases, can lead to wrongful convictions if improperly admitted, highlighting the need for careful assessment of its necessity and reliability.
  • Expert evidence, particularly in sexual assault cases, can contribute to wrongful convictions when it is improperly admitted, often due to the impressive credentials and scientific jargon of the expert.
  • In judge-alone trials, it's crucial to determine the admissibility of expert evidence to prevent jurors or judges from relying too heavily on expert opinions and to ensure the evidence has a unique degree of special knowledge to assist in reaching a just conclusion.
  • Expert evidence can be wrongly admitted in cases of wrongful convictions when judges fail to assess whether the evidence is truly needed to interpret a complainant's testimony.
  • Expert evidence was helpful but not necessary, and its incorrect use led to potential issues with assessing the credibility of complainants.
• 38:18 ⚠ Expert evidence can be misused in courts, leading to wrongful convictions, by improperly bolstering complainant credibility and masking weaknesses in testimony.
  • Prosecutors can improperly use expert witnesses by posing hypothetical questions that mask weaknesses in a complainant's testimony and give it a false veneer of scientific reliability.
  • Experts are sometimes improperly used to vouch for the credibility of complainants, essentially testifying to the truthfulness of their evidence.
  • The court of appeal cautioned that overly complicated expert evidence can misdirect juries, but in one case, a corrective instruction was deemed sufficient to mitigate the issue.
  • The judge unduly relied on expert testimony to bolster the credibility of the complainant, effectively usurping their role by giving it significant weight in the decision.
  • Courts must remain vigilant and careful when assessing expert evidence to prevent wrongful convictions, as flawed expert testimony, such as the misuse of neuroscience and trauma in sexual assault cases, can cloud analysis and lead to unjust outcomes.
• 43:14 📚 The Court of Appeal's decision in this case sets a significant precedent that can help individuals fighting similar situations in the future.

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Duration: 0:43:56

WatchUrl: https://www.youtube.com/watch?v=wES4onuhtE4

Publication Date:2025-03-24T08:35:22Z

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