New & Notable: Use of Drug Sniffing Dogs - The Reasonable Suspicion Standard Elucidated

Two RCMP officers were monitoring traffic from their marked cruiser on the Trans-Canada Highway just west of Caronport, Saskatchewan. Benjamin MacKenzie was travelling in a car on that highway a mere two kilometres per hour over the posted speed limit but the officers observed the front of the vehicle pitch forward as it rapidly decelerated as it passed by the cruiser. The officers went after the vehicle intending to deliver a warning about speeding. By the time the officers had caught up to the vehicle, they found it pulled over on the side of the road.


Mr. MacKenzie apologized for speeding and promised to slow down. Unfortunately for Mr. MacKenzie, things took a bad turn because the police officer dealing with him made a number of the observations that would culminate in the officer deploying his drug-sniffing dog.  The officer believed that MacKenzie might be involved in an offence under the CDSA. The officer observed that:

  • MacKenzie’s hands were shaky—trembling when he handed over this licence and registration.
  • He was sweating—beads of sweat were forming on his forehead.
  • His breathing was very rapid and his carotid artery was pulsing very rapidly. This rapid breathing did not decrease even after he used his asthma medication. Indeed, his nervous reaction continued even after he was advised that the reason for the investigation was minor speeding infraction.
  • This level of nervousness was extremely high given the nature of the investigation.
  • The pinkish colour of MacKenzie’s eyes was suggestive of possible marijuana use.

Finally, MacKenzie gave inconsistent answers about the dates of his trip between Regina and Calgary. Beyond the inconsistency, the officer recognized from his training that the stretch of highway that they were on was a known drug route.

Based on all of these factors, the officer came to believe that MacKenzie might be involved in an offence under the CDSA. After MacKenizie declined to consent to a search of his motor vehicle, the officers used the narcotic detector dog that they happened to have with them to conduct a perimeter search. After the drug dog indicated the presence of narcotics, police arrested the driver. A search incident to arrest resulted in the police locating 31.5 lbs of marihuana in the rear hatch area.

At trial, the accused successfully challenged the use of the drug dog as unconstitutional. The Saskatchewan Court of Appeal reversed that decision holding that the finding of the lower court that the constellation of objective factors was sufficient to meet the reasonable suspicion standard.

Justice Moldaver, writing for himself and four of his colleagues in a 5:4 split of the court dismissed the appeal to the Supreme Court: 2013 SCC 50.  Applying the articulation of what constitutes reasonable suspicion set out by Justice Karakatsanis in Chehil 2013 SCC 49, he held that police may use sniffer dogs for routine crime prevention in contexts where people have a reasonable, but reduced expectation of privacy and the police have reasonable grounds to suspect that a search will reveal evidence of a criminal offence. Moldaver J declined to make a category-based decision on the constitutionality of the use of sniffer dogs by the police that will apply in all circumstances instead determining that the question should be considered on a case-by-case basis.

The definition and especially the application of the terms reasonable suspicion and reasonable grounds to believe is problem that has long plagued the criminal law. Reasonable people can differ on what particular factual circumstances constitute a reasonable suspicion. If it is defined or applied to an exceedingly high standard the reasonable suspicion standard is no different than the reasonable grounds to believe standard. If the standard is too low it becomes meaningless and can be nothing more than a hunch. It is in this context that the MacKenzie decision helpfully summarizes the principles articulated in Chehil regarding the definition of reasonable suspicion:

Reasonable suspicion must be assessed against the totality of the circumstances. Characteristics that apply broadly to innocent people and “no-win” behaviour — he looked at me, he did not look at me — cannot on their own, support a finding of reasonable suspicion, although they may take on some value when they form part of a constellation of factors.

Exculpatory, common, neutral, or equivocal information should not be discarded when assessing a constellation of factors. However, the test for reasonable suspicion will not be stymied when the factors which give rise to it are supportive of an innocent explanation. We are looking here at possibilities, not probabilities. Are the facts objectively indicative of the possibility of criminal behaviour in light of the totality of the circumstances? If so, the objective component of the test will have been met. If not, the inquiry is at an end.

Assessing whether a particular constellation of facts gives rise to a reasonable suspicion should not — indeed must not — devolve into a scientific or metaphysical exercise. Common sense, flexibility, and practical everyday experience are the bywords, and they are to be applied through the eyes of a reasonable person armed with the knowledge, training and experience of the investigating officer.  [¶71-73] [Emphasis added].

Justice Moldaver openly acknowledges that the acceptance of the less demanding reasonable suspicion standard by the Supreme Court of Canada to things such as the use of drug sniffer dogs will have consequences for Canadian—including innocent ones:

The reasonable and probable grounds standard is a more demanding standard than the reasonable suspicion standard. It follows inexorably from this that more innocent persons will be caught under a reasonable suspicion standard than under the reasonable and probable grounds standard. That is the logical consequence of the way these standards have been defined.

However unappealing that result may be, we should candidly acknowledge that it is the foundation on which Kang-Brown, A.M., and the other reasonable suspicion cases have been built. Indeed, Karakatsanis J. does just that in Chehil, explaining that the “factors that give rise to a reasonable suspicion may also support completely innocent explanations” because the “reasonable suspicion standard addresses the possibility of uncovering criminality, and not a probability of doing so” (para. 32 (emphasis in original)). We accept this cost to individual privacy as a reasonable one in part because properly conducted sniff searches are “minimally intrusive, narrowly targeted, and highly accurate” (Chehil, at para. 28). In short, we have judged the trade-off between privacy and security to be acceptable. [¶85-86]

One final note-worthy aspect found in MacKenzie is Moldaver J’s inclusion of the officer’s training and field experience as being the prism through which the officer’s subjective belief was objectively reasonable:

Looking at the totality of the evidence through the lens of an officer with training and field experience in the transportation and detection of drugs, I am satisfied that Cst. Sperlie’s subjective belief that the appellant might be involved in a drug-related offence was objectively substantiated. Accordingly, Cst. Sperlie had reasonable suspicion that the appellant was engaged in a drug-related offence.  [¶83] [Emphasis added]