Graat v. The Queen, [1982] 2 S.C.R. 819, is the leading case decided by the Supreme Court of Canada

Supreme Court of Canada

The Supreme Court of Canada is the highest court of Canada and is the final court of appeals in the Canadian justice system. The court grants permission to between 40 and 75 litigants each year to appeal decisions rendered by provincial, territorial and federal appellate courts, and its decisions...

 on the admissibility

Admissibility

Admissibility may refer to:* Admissible evidence, evidence which may be introduced in a court of law.* Admissible decision rule, in statistical decision theory, a rule which is never dominated.* Admissible rule, in logic, a type of rule of inference....

 of opinion evidence

Opinion evidence

Opinion evidence refers to evidence of what the witness thinks, believes, or infers in regard to facts, as distinguished from personal knowledge of the facts themselves. In common law jurisdictions the general rule is that a witness is supposed to testify as to what was observed and not to give an...

. The Court held that lay persons may give opinion evidence, which is normally reserved only for expert witnesses, where the opinion is so closely infers fact that it is a "compendious statement of fact". The determination is left to the discretion of the trial judge.

Background

Anthony Graat was pulled over by London, Ontario

London, Ontario

London is a city in Southwestern Ontario, Canada, situated along the Quebec City – Windsor Corridor. The city has a population of 352,395, and the metropolitan area has a population of 457,720, according to the 2006 Canadian census; the metro population in 2009 was estimated at 489,274. The city...

 police. To the officers he appeared intoxicated and so was arrested for impaired driving. At the scene of the arrest Graat complained of chest pains and so was taken to the hospital. Due to the stop at the hospital the two hour limit in which to get a breathalyzer

Breathalyzer

A breathalyzer or breathalyser is a device for estimating blood alcohol content from a breath sample...

test expired. At trial the only evidence the Crown could lead with was the testimony of the police officers. The defence tried to have the evidence excluded as opinion evidence.

Reasons of the court

Justice Dickson, writing for a unanimous court, held that the statements were admissible. Despite their experience, the police officers were not considered experts for determining intoxication and so were limited to giving testimony on observed facts. The trial judge however had discretion to admit certain types of opinion evidence where the distinction between opinion and fact are not clear. Dickson rejects the "ultimate issue" doctrine, which prohibits opinion evidence on matters that concern the ultimate legal issue of the trial.