Expert Evidence

Last week, the Ontario of Appeal heard the appeal of the Christy Natsis case. You may recall the Natsis trial a few years ago: a Pembroke dentist who was charged with impaired driving and driving with over 80 milligrams of alcohol in her system. Ultimately, after 55 days of trial, the trial judge excluded the breath readings because of violations of Ms. Natsis’s rights, but convicted her of impaired driving causing death, largely on the expert testimony of the Ontario Provincial Police reconstructionists. The main issue on appeal is whether the trial judge properly allowed the police officers to testify as an expert and provide opinion evidence on the nature of the accident.

Generally speaking, opinion evidence is inadmissible in court. Witnesses, whether they are civilians or police officers, are not allowed to testify about their opinion of matters, because courts have found that a person’s opinion of a matter in the trial is simply not relevant. However, for every rule there is an exception and opinion evidence may be admitted when it is expert evidence and where it meets a certain test. To be admitted, the party trying to admit the evidence needs to meet four criteria:

•1. That the evidence is relevant to an issue at trial;

•2. That the opinion evidence is necessary to assist the judge or the jury because it deals with information that is outside common experience and knowledge;

•3. That there is no other evidentiary rule that should exclude the evidence; and

•4. That the evidence should come from a properly qualified expert.

Another important feature of an expert and their opinion, and one of the main issues in the Natsis trial is the impartiality and objectivity of the expert witness. While an expert witness is either hired by the Crown or the defence, they are required to be impartial and unbiased towards either party in giving their opinion. At the Natsis trial, defence argued that the OPP officers offered to give expert evidence demonstrated a bias, partiality and lack of independence when offering their opinion. Ultimately the trial judge disagreed and admitted most of that evidence. Now it will be up to the Ontario Court of Appeal to determine whether the trial judge decided in error and it may provide some guidance on when police officers can be qualified as experts.

Dealing with the possibility of expert evidence from the Crown can involve high stakes. Not only is there the expert opinion that needs to be reviewed and scrutinized, but also the qualifications and the independence of that witness. The criminal justice has known the tragedy of Dr. Charles Smith, the former pathologist who was the head pediatric forensic pathologist at the Hospital for Sick Children in Toronto and whose “expertise” and expert evidence resulted in many wrongful convictions and a public inquiry that un uncovered the flaws in a system that so readily accepts the expert opinion of an individual without adequate scrutiny.


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