Supreme Court Upholds Sniffer Dog Searches

In a pair of recent decisions, the Supreme Court of Canada upheld sniffer dogs searches that trial court judges had ruled unconstitutional. The use of sniffer dogs engages section 8 of the Charter of Rights and Freedoms, which protects against unreasonable search and seizure. In the first case, R v. Chehil, 2013 SCC 49, the court unanimously held that the sniffer dog search did not violate section 8. In the second case, R v. MacKenzie, 2013 SCC 50, the court was divided, with a narrow majority holding that there was no section 8 violation.

R v. Chehil

While analyzing the passenger manifest for an overnight flight from Vancouver to Halifax, police grew suspicious of Mandeep Singh Chehil. The reasons included him having a one-way ticket, him being one of the last passengers to purchase a ticket, him travelling alone, him paying for his ticket in cash, and him checking one bag. The police deployed a drug detection dog to inspect Chehil’s checked bag. After the dog indicated that narcotics were present, the police arrested Chehil and found three kilograms of cocaine in the bag. According to the trial judge, the police did not have reasonable suspicion to bring in the sniffer dog and the dog’s performance was not sufficiently reliable to render the search of Chehil’s bag reasonable. The police’s actions thus violated section 8 of the Charter. The Court of Appeal disagreed and allowed the Crown’s appeal.

Writing for the unanimous Court, Justice Karakatsanis noted that reasonable suspicion is concerned with possibilities rather than probabilities, which necessarily means that police will sometimes reasonably suspect innocent people. Nevertheless, the proper use of sniffer dogs based on the reasonable suspicion of an individual complies with the Charter because these searches are “minimally intrusive, narrowly targeted, and can be highly accurate.” Justice Karakatsanis emphasized that reasonable suspicion must be assessed in light of the totality of a case’s circumstances. Such an inquiry “must be fact-based, flexible, and grounded in common sense and practical, everyday experience.” A merely “generalized” suspicion is not sufficient, for such a standard would capture too many innocent people. Moreover, police cannot simply disregard exculpatory, neutral, or equivocal information when assessing the various factors in a case. Nevertheless, “the obligation of the police to take all factors into account does not impose a duty to undertake further investigation to seek out exculpatory factors or rule out possible innocent explanations.” Though the police are required to point to particular conduct or evidence of criminal activity to ground reasonable suspicion, the conduct itself need not be criminal, nor the evidence be evidence of a specific known criminal act. Ultimately, one central question guides the analysis: “is the totality of the circumstances, including the specific characteristics of the suspect, the contextual factors, and the offence suspected, sufficient to reach the threshold of reasonable suspicion?”

The onus is on the Crown to demonstrate that a reasonable person in the police officer’s position would reasonably suspect that the individual is engaged in criminal activity. While noting that a police officer’s training and experience may provide them with an “objective experiential” basis for reasonable suspicion, Justice Karakatsanis stressed that this does not mean that hunches or intuition are sufficient, or that deference is owed to the police officer’s view of the circumstances: “A police officer’s educated guess must not supplant the rigorous and independent scrutiny demanded by the reasonable suspicion standard.”

Justice Karakatsanis noted that the reliability of a particular police dog is relevant in determining whether a particular search was reasonable. Judges may consider the testing of dogs in controlled settings and the results of field deployment in assessing a particular dog’s reliability.

Though Chehil had a reasonable expectation of privacy regarding the content of his checked luggage, the Court held that the sniff search was reasonable. In the Court’s view, the trial judge erred in considering each of the factors leading to the police’s suspicions individually. Rather, the trial judge ought to have viewed them in their entirety. According to the Court, such an analysis indicates that there was reasonable suspicion to justify the sniff search. Further, the sniffer dog’s reliability and the absence of exculpatory explanations were sufficient to raise the initial reasonable suspicion to probable grounds for Chehil’s arrest.

R v. MacKenzie

During a highway traffic stop, a police officer grew suspicious of Benjamin Cain MacKenzie. MacKenzie had been driving in an erratic manner, exhibited a high degree of nervousness, had eyes of a pinkish hue, had taken a suspicious course of travel, and gave contradictory answers regarding his travel dates. The police officer employed a sniffer dog, ultimately finding marijuana in the car’s trunk. The trial judge held that there was not reasonable suspicion, and that the sniff search violated section 8. The Court of Appeal reversed this decision.

In contrast to Chehil, the justices were closely divided on MacKenzie. Justices Abella, Rothstein, Moldaver, Karakatsanis, and Wagner comprised the majority, with Chief Justice McLachlin and Justices LeBel, Fish, and Cromwell dissenting.

Writing for the majority, Justice Moldaver noted that “while it is critical that the line between a hunch and reasonable suspicion be maintained to prevent the police from engaging in indiscriminate or discriminatory practices, it is equally vital that the police be allowed to carry out their duties without undue scepticism or the requirement that their every move be placed under a scanning electron-microscope.” In the majority’s view, the police officer had reasonable suspicion that MacKenzie was engaged in a drug-related offence and it was thus appropriate to bring in the sniffer dog. There was no Charter violation, so the marijuana was admissible.

Justice Moldaver emphasized the importance of maintaining a distinction between the detention and search issues in the case, since these involve different Charter rights. While a police search involves section 8, detention engages the liberty right in section 7. Accordingly, the sniff search and the detention must be independently justified. Both were indeed justified in the majority’s view, so the appeal was dismissed.

Writing for the minority, Justice LeBel emphasized the need for “[r]igorous judicial scrutiny” of sniff searches in order to maintain the proper balance between enabling effective law enforcement and protecting the public’s privacy rights. Courts should not be so deferential to law enforcement that police are able to draw on their field experience to create broad categories of putatively suspicious behaviour that could encapsulate nearly anyone. When applying the modified objective standard that requires determining whether there was reasonable suspicion from the perspective of a reasonable person standing in the investigating officer’s shoes, courts should not show the investigating officer’s testimony any particular deference. To show such deference would undermine the objective aspect of the analysis. Justice LeBel noted the importance of the officer’s credibility in determining whether there was reasonable suspicion. Accordingly, appellate courts should keep a trial judge’s concerns over the officer’s credibility in mind when reviewing a case.

The minority concluded that there was not reasonable suspicion to conduct the sniffer dog search in this case. The police “relied on markers that apply broadly to innocent people, or markers only of generalized suspicion … which were at best highly equivocal.” As a result “taking into account the officer’s training and experience, the totality of the circumstances, including neutral and equivocal factors, and showing due deference to the trial judge’s credibility concerns with regard to the officer’s observations” the minority concluded that these factors could not collectively support a logical inference of criminal behaviour. MacKenzie’s section 8 rights were thus violated.


In two cases from 2008, the SCC ruled 6-3 that the use of sniffer dogs was unjustified in the particular circumstances. The first case involved a man staring at an RCMP officer in a bus station, agreeing to allow the officer to look in his travel bag, and then pulling away the bag when the officer reached for it. The officer brought in a sniffer dog that indicated there were narcotics in the bag. The second case involved a dog sniffing an unattended backpack as part of a school’s zero tolerance drug policy. It may be tempting to view the different outcomes in the 2008 and 2013 sniffer dog cases as evidence of a shift toward greater deference to police resulting from Prime Minister Stephen Harper’s appointments to the Court. However, these recent cases are not directly analogous to those from 2008. The constellation of facts in both Chehil and MacKenzie suggest greater justification for the use of sniffer dogs than in Kang-Brown or A.M. It must also be noted that the Chehil decision was unanimous. It would not be surprising if the current Prime Minister’s appointments do indeed lead to a Supreme Court that is less willing to rule against police and in favour of an accused’s Charter rights. But whatever the merits of the 2013 sniffer dog decisions may be, they are not persuasive evidence of this occurring.

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