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  • Lewis Waring

Reliability of Sniffer Dogs - Lauren Gowler

Who let the dogs out? This familiar phrase, popularized in song, figuratively characterizes similarities between men and dogs. This is one of the many prevailing efforts by society overall to humanize and correspondingly place our trust in dogs. They are after all “man’s best friend”, exhibiting, imagined or not, all of the best human characteristics. Is it a surprise that they’ve been elevated to the position of police “sidekick”? Whereby, how the “sidekick” behaves, determines whether a citizen’s rights to a reasonable search and seizure can be abused.

The reality is that dogs are trained. Their behaviour is tailored to how and what they are taught and how their handler manages them. They are beholden to their master and are undoubtedly eager to perform in a way that makes their handler happy. The feeling is mutual as the proud handler is inevitably eager to tout the positive results and performance of their canine companion. Are they independent and objective? Is there wide variances in the performance standards of handlers and their dogs? Many studies have suggested that these are valid concerns as they relate to the erosion of citizen’s rights. The issue is that law enforcement understandably would prefer expedience. The danger is when the practical idea of “sniffer dogs” is used as an investigative tool to circumvent a search warrant traditionally considered and issued by a judge.


In order to frame and illustrate this issue, let’s examine a study done by the Australian Government, started in 2012, whereby statistics of police drug detection deployments and seizures under the Controlled Substances Act were annually released (1). The 2018-19 report notes, for example, that there were 3384 indications where a drug dog indicated the presence of a drug odour on an individual or in a vehicle (2). Of those 3384 indications, only 436 resulted in the actual detection of drugs or paraphernalia on the individual or in the vehicle when subsequently searched (3). 2245 of the 3384 were indications of “residual admissions”, whereby drugs weren’t actually found, but the individual being searched admitted to having previously been in possession, in contact or having stored illicit substances in their vehicle (4). Finally, the remaining 703 of the 3384 indications were designated as “residual denies” (5). This is where individuals who, despite the dog’s indication, denied having previously been in possession, in contact or having stored illicit substances in their vehicles.

The interesting part of this is that of all the indications, only 12.8% resulted in the police actually finding drugs. More troubling is the 20.7% of indications whereby the dog alerted -- but the police didn’t find anything and the individual insisted that they had not been in previous contact with illicit substances. Furthermore, although we all seem less inclined to defend the rights of the remaining suspicious 66.5%, the fact is that at the time of search these individuals were not breaking any drug possession laws. With respect to this study, I think that it’s reasonable to assess a “dog sniffer” success rate of 12.8% and a failure rate of 87.2%: not impressive by any standards and a long way from the purported success rate of sniffer dogs in Canada.

If the Australian study shows us anything, it suggests that in Canada we’re perhaps seeing less than half of the equation. I think it’s reasonable to assume that Australian and Canadian dogs as well as their handlers and trainers would share the same competencies, flaws, and characteristics. The difference in reported success rates is puzzling. Could this be attributed to reduced transparency within the Canadian law enforcement community? The police and RCMP are undoubtedly reluctant to publish annual statistics about the breakdown of sniffer dog indications. There is simply and understandably inherent bias built into the system. Obviously, law enforcement is interested in supporting this shortcut to search warrants. Consequently, it seems the only sniffer-dog criticisms the public are privy to are cases where the police actually find drugs and the accused, who is facing charges of possession or trafficking of drugs, is trying to prove that the search was unreasonable. The main thrust of these challenges under section 8 of the Canadian Charter of Rights and Freedoms (“the Charter”) is to exclude the recovered evidence from trial under section 24(2) of the Charter. The accused might be arguing that the police didn’t meet the “reasonable suspicion” threshold to deploy their dogs for a sniff search or instances where a dog’s false indication leads to an unnecessary arrest.

Importantly, what we’re presumably not seeing are the occasions whereby police use their “sniffer dogs'' and don’t find drugs. These examples of unreasonable search obviously don’t make it into the courts. Only the most confident, offended and zealous citizen, who has extra time and money, would pursue the matter in a court setting. Those with less indignance, less money, and a greater propensity to have perhaps been guilty of possession at a different point in time, are most certainly not going to be pursuing the matter in court. Mostly, I would imagine anyone who endures being stopped by the police and subjected to a large, frantic police dog sniffing them and their possessions is very relieved to be allowed to simply continue on their way. As the police get smaller in the rear view mirror, the thought of launching a complaint for a section 8 Charter right violation is not even a consideration or something they are even aware of. I would also suggest that most police officers in these circumstances are well versed at seeding doubt and guilt in people about whether in fact they had been in contact with drugs somehow thus further ensuring compliant behavior. In Canada we are compliant people who simply prefer to go about our own business and are not overly inclined to take authority figures to task for indiscretions. The danger of this obviously is the threat to a Canadian’s Charter rights.

American Professor Lawrence Myers, an expert of dog olfaction at the Auburn University College of Veterinary Medicine, expressed it well: “It’s a search warrant on a leash. It’s such an enormous back-door entry into search and seizure without a warrant” (6).


When the Supreme Court of Canada (“the Court”) first dealt with sniffer-dogs in 2008, with the cases of R v Kang-Brown (“Kang-Brown”) and R v AM (“AM”) and then later in 2013 with R v Chehil (“Chehil”) and R v MacKenzie (“MacKenzie”), the Court decided that it would deviate from the Hunter v Southam Inc (“Hunter”) standards that Justice Dickson had set in 1982 (7). Prior to executing the search, Hunter required police to convince a judge that there was “reasonable and probable grounds'' that a crime was being committed and that they were requesting a warrant in order to search (8). By sliding through Dickson’s “feasibility” exemption, these four cases allowed Canadian police to execute warrantless searches by simply satisfying the lower standard of “reasonable suspicion” and potentially facing a judicial review after the search (9).

In Chehil, the Court stated that this lower standard of reasonable suspicion would engage the “reasonable possibility, rather than the probability” (10). The police had to have a reasonable belief that the individual might be involved in criminal activity. However, this threshold of “reasonable suspicion” couldn’t be satisfied by an officer’s hunch, educated guess or mere speculation (11). It needed to be “reasonable” -- established through evaluating the totality of the circumstances, and based on objectively ascertainable facts (12).

If the police can satisfy the requisite “reasonable suspicion” threshold, then they can employ the sniffer dog to search for drugs without prior judicial authorization -- aka no search warrant. From here, an officer can use a positive indication from their sniffer dog to establish “reasonable and probable grounds” in order to arrest the individual or perform a “search incident to arrest” -- all without judicial authorization (13). At that point, the police can arrest the individual without actually having laid eyes on the drugs. The police base their further actions -- which have the effect of depriving an individual of their liberty -- on the conduct of a dog.

In Kang-Brown, the Court stated that the high accuracy of sniffer dogs that were properly trained and deployed was the key to endorsing a reasonable suspicion standard for sniff searches (14). However, this relied on the dogs and their handlers being properly trained, properly deployed, and appropriately evaluated. For example, in Kang-Brown, Justice Lebel criticized the trial judge’s overgeneralization and extrapolation of the statistics of one sniffer dog to the performance of all sniffer dogs (15). “The consequences of a false indication by a sniffer dog can be severe,” Justice Karakatsanis comments in Chehil, “[i]f the police make use of a dog whose indications cannot be taken as a reliable sign of the presence of the smell of drugs, the false positive resulting from the dog's unreliable nose could lead to unnecessary arrests”.(16) In order to determine the constitutionality of a sniffer-dog search, the Court evaluates two primary factors: (1) reliability of such searches and (2) their non-invasive nature. In Chehil, Justice Karakatsanis discusses some of the factors that should be considered when examining the reliability of dogs (17). Building on some of the concerns she presents, I will contemplate a few of the potential issues of sniffer dogs.


As we saw in the Australian study, because of a dog’s ability to detect the smell of illicit substances -- sometimes the sniffer dog will be unable to distinguish between residual odours lingering on contaminated items rather than the presence of actual drugs (18). Karakatsanis J suggested that in these situations where “the smell of drugs from contaminated property becomes pervasive, the utility of an indication by smell is diminished. In environments with high contamination rates, a dog may be inherently unreliable” (19). Nonetheless, she suggested that this shouldn’t count against a dog’s performance record in general but that handlers should keep records on whether a dog is exceptionally prone to false alerts or detecting residual odours (20). This creates two concerns:

  • detecting residual odours is not an exact science, relying mostly on admissions by the detained. I think that sniffer dogs should be judged on whether there are drugs found or not; and

  • Karakatsanis J suggests that handlers should be the ones to grade their own performance. I think this is a slippery slope.

There is a strong incentive for handlers to ensure that their dogs are seen as reliable. If an officer who is trying to justify performing a search vouches for the reliability of a dog -- whose alert justifies a warrantless search -- there seems to be no reason to question him. The dog potentially affirms the police and the police affirm the dog. It’s a convenient arrangement. There is obvious incentive to exaggerate a dog’s reliability as it is a gateway to acquire probable cause to search when it wouldn’t otherwise be available.

It seems, despite obvious opportunities for abuse of power, inherent bias, a lack of independent testing and reporting, there is a prevailing desire to place our faith in the reliability of “sniffer dogs’ and their handlers. The New York Times published a revealing article in late 2002 expressing some of the shortcomings of relying on “dog detectives” (21). Although this article is almost 20 years old the concerns expressed are still relevant today.

One of the first things that article explores is how standards for recording the performance of dogs vary from place to place and handler to handler. Dr. Adee Schoon, a scientific advisor for the Netherlands National Police Agency Canine Department, questioned the reliability of handler’s logs: “[w]ritten training logs, which are used to establish a dog’s reliability in court, are themselves often unreliable. There is a saying in Holland that the training log is a lie...if only because handlers want their dogs to look good” (22). The article suggests that many trainers and handlers, concerned about missing targets, deny that their dogs sound false alarms and thus do not record them, especially if they occur in the field. They argue instead that the “dog is picking up a faint trace of a substance that was once present”, or that a “handler caused the dog to err” (23). Thus, there appears to be difficulties in accurately and objectively measuring a dog’s reliability.

Furthermore, handlers can actually induce errors in their dog’s performance by “pulling their dogs away from things they are investigating, by letting them search too long in a specific place, or by inciting the dog through some gesture, glance or emotion”. Trainers say that the handler’s message ''travels right down the leash” (24). Dr. Myers notes that “[p]oor handlers alone can cause a dog’s vaunted accuracy of 85 percent to 95 percent to plummet to 60 percent” (25). He further explains “dogs want rewards, and so they will give false alerts to get them. Dogs lie. We know they do” (26).

There are other factors, besides lingering odours, that can also hurt a dog's performance. Dr. Lawrence Myers suggests that certain types of weather can affect performance: “Dry, hot weather can cause the mucus in the dog's nose to dry out. Hot, humid weather brings early fatigue. Extreme cold kills scents, and the wind scatters them” (27). He also estimates that in any year, “35 percent of detection dogs temporarily lose their sense of smell because of illness, tooth decay or other physical problems” (28).

For an expert like Dr. Myers to express these misgivings should lead to further scrutiny of this policing tactic. The problem is variables: different dogs, different handlers, different provincial procedures. Few have been or are able to be subject to scientific testing. Police handlers are the ones responsible to record the alerts. There’s no doubt that some dogs have the ability to detect drugs if trained and handled correctly, but the biggest worry is that the dogs are being influenced by their handlers. It seems the only consistent theme is the belief that the end result justifies the means used to achieve it.


To examine this conundrum in the Canadian setting, let’s explore the 2018 case of R v Rigo (“Rigo”) (29). Here, the Supreme Court of British Columbia (“the BCSC”) was faced with a “partial sit” given by a sniffer dog and the police officer’s hasty response to use this ambiguous indication to further arrest and search the accused.

Corporal Catellier pulled over Rigo, the accused, during a Highway 1 traffic stop outside of Chilliwack, BC. When the officer approached the car and started talking with Rigo, he made a number of observations, including the

  • strong odour of cologne or air freshener coming from inside the vehicle;

  • the fact that the accused’s right arm and hand were shaking when he pulled over; and

  • the presence of multiple cell phones” (30).

These observations led the officer to believe he had “reasonable suspicion” that the accused might be involved in some type of drug-related activity. Thus, the officer deployed his dog, PSD Doods, to perform a sniff search. After circling Rigo’s vehicle, PSD Doods apparently gave an ambiguous half sit. In his testimony, the officer admitted that he did not “have the benefit of prior guidance as to what he could make from an ambiguous or partial sit indication” (31). Despite his uncertainty, the officer quickly proceeded to arrest Rigo and search the vehicle. He did this believing that his dog’s partial ambiguous sit -- despite being contrary to her training and past performance -- indicated that there were drugs in the car, conveniently confirming Corporal Catellier’s suspicion.

At trial, the main question before the Court was whether the officer’s subjective belief that his dog had intended to perform a sit was objectively reasonable as part of the analysis of the overall grounds. Corporal Catellier and the Crown tried to argue that PSD Doods was attempting to perform a “sit” but was thwarted by the curb (32). However, when watching the police camera footage, Mr. Andre Jimenez, an expert dog trainer, opined that the “dog was lackadaisical” and did not appear to be exhibiting any signs of being “in odour” (33). He said that when dogs smell drugs they are typically “happy, engaged, excited, and more alert” because they expect to be able to play with a toy as a reward (34). In addition, Jimenez criticized the officer’s conduct with PSD Doods:

  • the dog was wearing a retractable leash which inhibited the ability of the dog to freely search;

  • the handler engaged in too much by leading instead of following the dog;

  • the handler gave too many repetitive commands to the dog;

  • the handler was walking too close to the dog; and

  • the dog looked to the handler for direction and the handler had to point to the vehicle to get the dog to commence searching (35).

Justice Brundrett held that the partial sit did not indicate, as per its training, that there were drugs in the car, and that the officer was too quick to rely on his dog’s ambiguous behaviour (37). Thus, the officer did not have requisite grounds for his subsequent actions, rendering the arrest of the accused and search of his vehicle as unreasonable. With this Charter violation, Brundrett J held the recovered narcotics would be excluded from trial (38).

Ottawa defense lawyer, Michael Spratt, possibly best summarizes this case with the following comments: “[t]he dog and the signal that the dog gives, we’re relying on that to give the police officers what they don’t have, and that is, grounds to make an arrest, detain the person, start the criminal process. Those are pretty extreme powers” (39).

Perhaps what I take most from this case is the subjective interpretation of the dog’s behaviour. Police Officer Catellier interpreted that the dog indicated drugs present. At trial, expert dog trainer Jimenez interpreted differently. Therein lies the problem. This is not a scientific process but yet can lead to tough consequences. In closing, I concur with the urging of the appellant’s counsel in Chehil:

Clearly, from a national perspective, Courts across Canada should share these concerns. A drug detection dog in British Columbia or Ontario, for instance, may be assessed for reliability differently than dogs in Nova Scotia or Quebec. In fact, dogs within each Province may be assessed differently. The handler of a dog may rate the accuracy of that dog in a way that improperly inflates accuracy. With no uniform standards in place, there is substantial risk that innocent travellers may be subjected to the humiliation of detention and arrest based on the indication of an unreliable sniffer dog (40).

Canada needs accountable, independent and consistent training, testing and reporting standards for sniffer dogs, their handlers and trainers. I think absent of that the use of sniffer dogs needs to be re-evaluated.


  1. Australia, South Australian Government Data Directory, “Annual Reporting Data: South Australia Police and Controlled Substances Act 1984”, 14 December 2020, online:<www:// 8-4856-829e-4f5270fab4fa>.

  2. Ibid.

  3. Ibid.

  4. Ibid.

  5. Ibid.

  6. Mark Derr, "With Dog Detectives, Mistakes Can Happen" (December 2002), The New York Times, December 2002, [“Dog Detectives”].

  7. R v Kang-Brown, 2008 SCC 18 [Kang-Brown]; R v AM, 2008 SCC 19; R v Chehil, 2013 SCC 49 [Chehil]; R v MacKenzie, 2013 SCC 50; Hunter v Southam Inc, [1984] 2 SCR 145 [Hunter].

  8. Hunter, supra note 7.

  9. Richard Jochelson & David Ireland, Privacy in Peril: Hunter v Southam and the Drift from Reasonable Search Protections, (Vancouver: UBC Press, 2019) at page 92-93.

  10. Chehil, supra note 7, at para 27.

  11. Ibid at para 48.

  12. Ibid at para 29.

  13. Ibid at para 49.

  14. Kang-Brown, supra note 7, para 62-4.

  15. Ibid.

  16. Chehil, supra note 7, at para 49.

  17. Ibid, at para 48-54

  18. Ibid, at para 50.

  19. Ibid.

  20. Ibid.

  21. “Dog Detectives”, supra note 6.

  22. Ibid.

  23. Ibid.

  24. Ibid.

  25. Ibid.

  26. Ibid.

  27. Ibid.

  28. Ibid.

  29. R v Rigo, 2018 BCSC 1807 [Rigo].

  30. Ibid at para 27.

  31. Ibid at para 17.

  32. Ibid at para 45.

  33. Ibid at para 128.

  34. Ibid.

  35. Ibid at para 126.

  36. Ibid at para 143.

  37. Ibid at para 212.

  38. Ibid at para.

  39. Tyler Dawson, “If she doesn’t sit, you must acquit: Man beats drug charge thanks to sniffer dog’s ‘partial’ signal”, The National Post (January 25, 2019), online: <www://>

  40. Chehil, supra note 7, (Factum of the Appellant at para 94).


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