INDG 401 Lecture 9: LAWG-426-001 Mar 16
9 Jun 2018
School
Department
Course
Professor
Criminal Evidence
March 16: Opinion Evidence
Guest Lecture: Sergeant Detective Cédric Aubut will be presenting on Friday. He will discuss confessions,
important information on how evidence is gathered by interviewing suspects and witnesses. Also he will
cover the legal and practical constraints detectives must operate under in order to obtain admissible
evidence.
R. v. White Burgess [2015]
• idepedee of the epet; gies additioal "o ias" iteia fo ualified epet
Expert Evidence
• An expert is the helper/witness of the court. The expert is there to teach the jury/judge and provide
context for the evidence
• Expert evidence = opinion evidence
• Opinion evidence is presumptively inadmissible
• Admissibility of expert evidence always happens in a voir dire. Talk about the scope of the expert
evidence and present the expert by asking him/her questions about why the evidence meets 4
criteria
• Popular today for judges to limit the scope of the expert evidence (like language that the expert can
use)
R v Mohan (1994)
• Lead case on expert evidence
1. Relevant
2. Necessary (battle is usually here)
3. Absence of exclusionary rule (I.e. character evidence)
4. Must be a qualified expert
• Mohan and following cases tell us that once 4 criteria is met, expert testimony is admissible
• Later, realized that the expert evidence, even if meet all 4 criteria, was very prejudicial b/c we're
telling the jury that they just need to believe the expert ("ready made inference")
• Facts: pediatrician found guilty of 4 counts of sexual assault after trial judge excluded
the defence's expert evidence
• Issue: expert evidence to show that the defendant was not the type of person to commit that
specific crime
• Ultimate issue: mens rea: psychological profile (did he have the predisposition)
o What would be highly prejudicial? If he had the predisposition to commit the crime
• Outcome: expert evidence was inadmissible on grounds of necessity (p38)
• What the expert evidence was saying was highly prejudicial, which means it must have had even
more probative value, which means tt must be an established science
• P38 - I take the findings of the trial judge to be that a person who committed sexual assaults on
young women could not be said to belong to a group possessing behavioural characteristics that are
sufficiently distinctive to be of assistance in identifying the perpetrator of the offences
charged. Moreover, the fact that the alleged perpetrator was a physician did not advance the
matter because there is no acceptable body of evidence that doctors who commit sexual assaults fall
into a distinctive class with identifiable characteristics. Notwithstanding the opinion of Dr. Hill, the
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