Polygraph: The Law

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1.0 The Law of Polygraph

1.1 Admissibility of Polygraph Evidence in Canadian Criminal Courts

In R v Beland, the Supreme Court of Canada ruled that the results of polygraph examinations are not admissible as evidence in Canadian criminal courts. The SCC found that the polygraph is employed as a tool to determine and test the credibility of witnesses, and that it consequently offends well established rules of evidence, most notably (a) the rule against oath-helping, which prohibits a party from presenting evidence solely for the purposes of bolstering a witness’ credibility; (b) the rule against admission of past or out-of-court statements by a witness; and (c) the character evidence rule. The SCC also held that polygraph evidence is inadmissible as expert evidence, because the issue of credibility is a matter well within the experience of judges and juries. As such, no expert evidence with respect to the credibility of witnesses is required [1]. 

Furthermore, the SCC declared that the admission of polygraph evidence would:

  • disrupt proceedings
  • leave courts prone to time-consuming and confusing consideration of collateral issues;
  • deflect the focus of the proceedings from the fundamental issue of guilt or innocence;
  • lead to many complications resulting in no greater degree of certainty of the process; and
  • influence the trier of fact with the mystique of science despite being prone to human error.

The SCC concluded that evidence of this type should not supersede the role of the judge and jury to decide on matters such as the credibility of a witness, as trial by judge and jury – and not trial by machine – has long been the backbone of the Canadian criminal justice system [2]. 

1.2 Admission of Confessions

Although polygraph evidence is not admissible in Canadian criminal courts, a polygraph examiner may provide testimony where a confession has been obtained. A confession given during the course of a polygraph exam will be considered voluntary and admissible if certain conditions are met. The SCC in R v Oickle held that to determine voluntariness, a court must ask:

  1. Was the confession induced by threats or promises? Whether there has been a quid pro quo – or an exchange – for the confession will often determine whether it is voluntary.
  2. What were the means employed to elicit the confession? Confessions obtained by means of oppressive, distasteful, or inhumane conduct are less likely to be considered voluntary.
  3. Was the suspect of sound or operating mind when the confession was made? A suspect must be sufficiently aware of what he or she is saying and to whom he or she is saying it.

Was police trickery involved in obtaining the confession? While trickery, or minor acts of deception, are generally allowed, they cannot go so far as to shock the community [3]. 

The SCC ruled that a court should attempt to understand the circumstances surrounding the confession and ask if they give rise to a reasonable doubt as to the confession’s voluntariness. Once again, the relevant factors a court must consider include threats or promisesoppression, the operating mind requirement, and police trickery. A confession will not be admissible if it is given under circumstances that raise a reasonable doubt as to its voluntariness [4].

To similar effect see R v McIntosh [1999] OJ No 4842 at paras 20-42 (CA); see also R v Myers, [2007] OJ No 5395 (SCJ).

1.3 Charter Issues

An issue which sometimes arises in the context of polygraph interviews is whether or not a interviewee was detained and whether his status changed as a result of a polygraph examination or during the course of a post-polygraph inteview. In McIntosh the Ontario Court of Appeal considered the issue of detention as well as the issue of change in jeopardy. Where the jeopardy of an interviewee changes during the course of a post-polygraph interview, if the interviewee was not originally a suspect, there will be an obligation to advise the interviewee of his right to counsel: McIntosh @paras 43-53. 

McIntosh was distinguished in Chalmers where the interviewee began as a suspect and was advised of his rights, in short, there was no change in status: [2009] OJ No 1254 (CA) - see also R v Barton, [1993] OJ No 1231 (CA). 

For further consideration of this issue see R v Myers, [2007] OJ No 5395 (SCJ).

1.4 Admissibility of Polygraph Evidence in Canadian Civil Courts

The admissibility of polygraph evidence in civil courts varies from province to province. In Ontario, polygraph results are generally inadmissible because they usurp the very function of the trier of fact. In Petti v George Coppel Jewellers Ltd., the trial judge held that in some circumstances, the questions and answers on a polygraph test may be admissible if the answers constitute an admission against interest. The trial judge further held that a party’s volunteering to take a polygraph test may be admissible as evidence of cooperation. Barring these circumstances, however, test results are deemed inadmissible in order to preserve the jurisdiction of the courts [5].

Conversely, in Quebec courts, the opinion of a polygraph examiner as well as polygraph evidence are admissible. In Lamothe v General Accident Insurance Company, the trial judge referred to polygraph testing as innovative scientific technique that is admissible in evidence. The trial judge also held that the opinion of the polygraph examiner is admissible evidence because his function is to interpret specific physiological findings and determine whether they correspond to those of a person who is telling the truth, which falls outside the abilities of the trier of fact [6].


1 R v Beland, [1987] 2 SCR 398.


R v Oickle, 2000 SCC 38, 2 SCR 3.


5  Petti v George Coppel Jewellers Ltd., [2008] OJ No 945.

Lamothe v General Accident Insurance Company via Polygraphia, supra note 2.