How Accurate are Drug Sniffing K-9s?

November 22, 2023 Criminal Defense, Drug Charges

Law enforcement agencies around the world are beginning to question the reliability of police K-9s trained to detect the scent of certain illegal substances.

While both State and Federal police have utilized police canines for their enhanced sight and smell, recent data suggests that the alerts given to the canine handlers may be wrong more often than right. Two studies—one out of Australia and the other out of Chicago—point out the inconsistencies in drug detection success rates.

This page will provide relevant definitions and the use of police K-9s in Florida. We will provide the data from two recent studies focused on the accuracy of drug detection K-9s, as well as include two U.S. cases that involved the detection of drugs from a K-9.


The following glossary was published by the Florida State University (FSU) Police Department:

  • Canine (K-9) – A dog that has been procured and specially trained to execute a number of specific law enforcement and public service tasks which make use of the canine’s speed, agility, and sense of smell.
  • Canine handler – A sworn member specifically trained in the care, handling, and training of a canine for the use of law enforcement.
  • Canine Team – A canine handler and their assigned dog.
  • Multi-Purpose Canine – A dog that has been trained in both patrol and detector phases of training.
  • Detector Canine – A dog that has been trained in detecting and locating the odor of specific substances (i.e., narcotics, explosives, etc.).

Police K-9s in Leon County

The Leon County Sheriff’s Office (LCSO) has established a Canine Unit that is utilized by its members and other police agencies in the community. Their page highlights how police dogs are considered “full-fledged law enforcement officers” and are used to work alongside the canine handler and team.

The common use of K-9s in law enforcement is due to their “remarkable smelling and hearing senses.” LCSO explained that each of their canine teams must undergo a minimum of 480 hours of training, plus an additional 200 hours of specified narcotics training. Once the Canine Team passes their certification, they can perform their patrol duties, which may include any of the following:

  • Searching for hidden offenders;
  • Locating missing persons;
  • Tracking down suspects;
  • Detecting narcotics; and
  • Conducting public service canine demonstrations.

Recent Studies Suggest Inaccurate Analysis from Drug Sniffing Dogs

A recent study shared on Norml’s website, the national organization for the reform of marijuana laws, analyzed the accuracy of alerts that drug sniffing dogs in Australia provided to members of the Australian Parliament.

The study covered over 94,000 drug related searches that took place in New South Wales. There was an overwhelming majority of searches that did not accurately identify the presence of an illegal substance. Between 2013 and June 30, 2023, the study found that nearly 71,000 searches prompted by drug sniffing dogs resulted in no illicit drugs being found.

A report in The Sydney Morning Herald stated, “The worst year for drug-detection dogs was 2014, when only 21 percent of the 14,213 searches resulted in illicit drugs being found; the best was two years later in 2016, where 32.5% of the 8,746 searches were accurate.” 

A U.S. based study was conducted by the Chicago Tribune, which focused on three years of cases where law enforcement employed drug sniffing dogs to search for illicit substances out of cars in suburban Chicago.

The result of the study found that out of all the cases where the K-9s alerted their handler about suspicious vehicles, only 44 percent of them were accurate in finding drugs. The following provides an explanation from the study:

“Dog-handling officers and trainers argue the canine teams’ accuracy shouldn’t be measured in the number of alerts that turn up drugs. They said the scent of drugs or paraphernalia can linger in a car after drugs are used or sold, and the dogs’ noses are so sensitive they can pick up residue from drugs that can no longer be found in a car.”

However, the Tribune interviewed several dog experts on the topic of canine handling for drug sniffing dogs. The dog experts almost unanimously placed the blame on the handler.

“Dog handlers may accidentally cue alerts from their dogs by leading them too slowly or too many times around a vehicle,” said Lawrence Myers, a professor at Auburn University who specializes in detector dogs.

Current Standings on Drug Detection K-9s

Despite data alluding to the inaccuracies provided by drug detection K-9s, they are still used in the State of Florida and the rest of the United States. The Supreme Court ruling in Illinois v. Caballes (2005) provided that the use of a drug detection K-9 during a routine traffic stop does not violate the Fourth Amendment, which protects citizens from unreasonable search and seizures.

In the case of Florida v. Harris (2013), Clayton Harris was stopped by Liberty County Officer William Wheetley on June 24, 2006. The report indicated that Wheetley pulled Harris over for an expired license plate. Wheetley claimed that Harris was acting “visibly nervous” while he approached the vehicle. When the officer requested that he search the car, Harris refused. Wheetley then retrieved Aldo, his German shepherd K-9 trained in detecting certain narcotics. While Wheetley walked Aldo around the car as per standard K-9 procedure, the dog alerted Wheetley near the driver’s side door that he sniffed out potential drugs.

Officer Wheetley explained that he had probable cause to search Harris’ vehicle, which revealed 200 loose pseudoephedrine pills, 8,000 matches, a bottle of hydrochloric acid, two containers of antifreeze, and a coffee filter with iodine crystals. Wheetley arrested Harris, and after he gave the proper Miranda warnings, the suspect allegedly admitted to routinely “cooking” methamphetamine. Harris was charged with possession of pseudoephedrine and the manufacturing of methamphetamine.

After Harris was released on bail, he was pulled over once again by Wheetley and Aldo. This time Aldo alerted his handler again, implying that Harris had illicit substances in his possession. However, the resulting search revealed nothing of interest.

Harris and his defense team requested a hearing for the suppression of evidence, claiming that Aldo’s alert had not given probable cause for the second alert. Wheetley testified about both his and Aldo’s extensive training for detecting drugs, which highlighted the 120 and 160-hour drug detection courses completed by both Wheetley and his K-9. The trial court denied the request, which was later reversed by the Florida Supreme Court. Their ruling claimed that an officer who fails to keep records of the field performances and the false alerts from drug detection K-9s could “never have probable cause to think the dog is a reliable indicator of drugs.”

The case was then taken by the U.S. Supreme Court, who focused on establishing that an officer has probable cause to conduct a search when “the facts available to [him] would ‘warrant a [person] of reasonable caution in the belief” that evidence of a criminal act is present. Since there were training records presented to establish Aldo’s reliability as a drug detecting K-9, and Harris and his attorneys failed to undermine that specific information, the Supreme Court reversed the Florida Supreme Court judgement and concluded that Wheetley had probable cause to search Harris’ vehicle.

Important: In the state of Florida, a police dog with a “single purpose” such as one that is only trained to detect illicit drugs, is not required to obtain, or carry certification. On the other hand, a dual-purpose dog, such as one trained in both drug detection and apprehension, are required to carry a certification through the Florida Department of Law Enforcement (FDLE).

To read more about routine traffic stops involving drug detecting K-9s and possible defenses to use if facing a similar charge, find our blog post here.

Contact a Tallahassee Defense Attorney

Cases involving canine teams can often be complex, but it is important that you know your rights when stopped by an officer and their search K-9. If you were recently stopped by an officer and a drug detecting K-9 where you believe your rights were violated, it is in your best interest to hire a defense attorney. An experienced attorney will be able to review the case details and formulate a strong defense to fight the charges against you.

Don Pumphrey and his team have a deep understanding of search and seizures and are prepared to fight for you in court. Contact the criminal defense attorneys with Pumphrey Law Firm and receive a free consultation by calling (850) 681-7777 or leave an online message on our website.

Written by Karissa Key

Back to Top