- The traditional function of a juror is to apply his or her own daily experiences to determine whether a witness is being truthful, after hearing all the evidence. In other words, our judicial system has long deemed that judges and juries are sufficiently qualified to assess credibility and reliability. Expert evidence is not required to determine witness veracity, and therefore the admission of polygraph evidence would be contrary to the well-established principles of evidence.
- The admission of polygraph evidence would not serve any purpose which is not already served by the rules of evidence. In the opinion of the Supreme Court, the admission of polygraph evidence would cause delays and complications, which would not improve the degree of certainty in the judicial process that currently exists.
While the result of a polygraph is inadmissible, the fact that litigants offered to take a polygraph test was entered as evidence by the Ontario Court of Appeal in Whiten v Pilot Insurance Co. (1999),42 OR (3d) 641. In that case, the Ontario Court of Appeal stated that the litigants’ offer to take a polygraph test was part of the total evidence showcasing the litigants’ good faith and willingness to cooperate. This case was appealed to the Supreme Court of Canada, but not as to the polygraph issue.
In the case of Petti v George Coppel Jewellers Ltd, 2008 Carswell Ont 1324, the Ontario Superior Court of Justice held that the questions and answers on a polygraph test may be admissible statements in certain situations, such as when an answer constitutes an admission against interest. The fact that a litigant had volunteered, offered or rejected to take a polygraph test was also deemed as acceptable evidence, although the Court noted that this evidence typically carries little weight. However, the Court echoed the sentiments of the Supreme Court in R v Beland and noted that use of a polygraph test result would usurp the function of the trier of fact and the result was therefore inadmissible.