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In recent years, courts across Canada have seen a surge in expert testimony on the “neurobiology of trauma,” especially in sexual assault cases. While this science can provide important insights into how trauma affects memory, there is a line that cannot be crossed: experts cannot be used to bolster a complainant’s credibility.
The Ontario Court of Appeal’s decision in R. v. P.J.C., 2025 ONCA 196 reinforces this boundary. In this case, the Court overturned a conviction and ordered a new trial after concluding that the Crown’s expert witness, Dr. Lori Haskell, had crossed that critical line.
Dr. Haskell’s testimony was intended to explain the complainants’ memory gaps through concepts like “impaired semantic encoding” and “dissociative amnesia.” She suggested that certain details, such as a child complainant not recalling whether ejaculation occurred, could be explained by their young age and limited understanding of sexual concepts.
However, the Court of Appeal determined that this went beyond merely providing context. Instead, it effectively framed the complainants’ memory gaps as indicators of past sexual abuse, cloaked in scientific authority. This kind of testimony, the Court found, dangerously blurred the line between evidence and argument, especially when jurors or judges may defer to an expert’s authority rather than weigh the evidence critically.
In judge-alone trials, like in P.J.C., the risk remains that judges may unconsciously give undue weight to expert opinions, especially when the evidence is presented with impressive credentials and complex jargon. The Court of Appeal warned that such testimony can blunt the effect of cross-examination and undermine the defence’s ability to test the evidence properly.
The Crown’s hypotheticals posed to Dr. Haskell mirrored the complainants’ experiences too closely, further risking the perception that the expert was endorsing the complainants’ credibility.
The Court made it clear: while scientific insights can assist the court in understanding trauma, they cannot be used to suggest that certain behaviours or memory gaps prove that abuse occurred. Doing so risks replacing the jury’s or judge’s fact-finding role with the expert’s opinion, something the justice system cannot allow.
For anyone facing sexual assault allegations, this case underscores the importance of challenging expert evidence that crosses into impermissible territory. Defence counsel must be vigilant in exposing when expert testimony is being used not to explain evidence but to improperly validate it.
At Neuberger & Partners, we stay at the forefront of evolving legal standards in sexual assault trials. Our team is experienced in dissecting expert evidence and challenging any attempt to use scientific language as a substitute for actual proof.
If you’re facing allegations influenced by trauma science testimony, or if you believe the evidence against you is being misinterpreted, contact Neuberger & Partners today for experienced, strategic criminal defence. Call us at 416-364-3111.
