Photo by Monika Wisniewska.

Teaching Old Dogs New Tricks, Literally: Can Police Dogs Be Un-Trained To Sniff For Cannabis?

Photo by Monika Wisniewska.


by Aaron Kase

on March 12, 2015

Law enforcement has a problem in states with legal cannabis: what to do about dogs that are trained to alert them to the cannabis plant’s distinctive odor? How they answer the question lies at the heart of our Fourth Amendment protections against unreasonable search and seizure.

Some jurisdictions are responding by putting their existing dogs through extinction training, meaning the animals are taught to no longer alert to marijuana. However, some experts question the utility of extinction training, and there remain unsettled legal questions in the event a dog does alert its handler to legalized pot. Even more worrisome, there is ample evidence that police actually have incentives to use dogs that over-alert, because it gives them cause to confiscate motorists’ money via civil forfeiture — even if they don’t find any illegal substances.

One major question is whether dogs can even be taught to reliably ignore an odor after spending their lives being rewarded for alerting to it. One long-time dog trainer says no.

“Marijuana extinction training is not going to be very effective because you have highly taught the dog to respond to that substance,” said Steven D. Nicely, owner and founder of K9 Consultants of America.

Nicely, who has four decades of experience working with and training police service dogs, says the behavioral science concept of spontaneous recovery means that you never know when an animal might revert to a previously trained behavior.

That matters because in most circumstances, a dog alert is all the police need to have probable cause to search your car, or your person.

“When you do the extinction training, you don’t know when spontaneous recovery is going to recur,” Nicely said. “As a result, the dog responds and you end up searching someone that has marijuana, but is in legal possession of it, so now you’re searching someone who’s not violating the law.”

The trainer isn’t the only expert who has doubts.

“Once you put an odor on a dog, it’s very difficult to get that odor off,” Lawrence Myers, a veterinarian neurophysiologist at Auburn University, and expert on dogs’ olfactory capabilities, said to, noting that “retraining is possible, but it takes time and scientifically valid testing to show that the dogs no longer alert to marijuana.”

Nicely says dogs that have undergone extinction training at the very least need to demonstrate through ongoing testing that they continue to ignore marijuana.

“If it was my option, I would have the dog totally removed from service, or certainly could not be used to provide probable cause,” he said. “Those responsible for training need to understand behavioral science and its application so they can take action to reduce the potential for false responses in the real world.”

However, the Supreme Court has ruled that one-time certification is all the dog needs to prove its bona fides. In the 2013 case Florida v. Harris, the Supreme Court unanimously confirmed that a certificate was sufficient for a dog to give probable cause to search a vehicle. The state argued, and the justices accepted, that law enforcement wouldn’t want to use inaccurate dogs, so they have no reason to be anything less than aboveboard.

“After all, law enforcement units have their own strong incentive to use effective training and certification programs, because only accurate drug-detection dogs enable officers to locate contraband without incurring unnecessary risks or wasting limited time and resources,” the Elena Kagan-written opinion states.

However, some certificates are awarded by for-profit trainers, who make more money if all their dogs pass. Other law enforcement agencies make their own certifications. There’s even strong evidence that prosecutors in Maryland fabricated a certificate after the fact to supposedly prove their dog’s alert was reliable in a drug case.

Furthermore, there are in fact very good reasons for police to use dogs that give false alerts. Leslie A. Shoebotham, a professor at the Loyola University College of Law, wrote an article in 2013 about two incentives police have to use unreliable dogs: Financial gain in the form of asset forfeiture, and the ability to racially profile potential suspects.

Police might be tempted to racially profile either because they think minorities are more likely to be involved in a crime, or less likely to go to court to get their assets back after seizure. The practice is unconstitutional, but the dog alerts provide a loophole. A 2011 study by the Chicago Tribune found that dogs correctly alerted their handlers to illegal substances during live traffic stops only 44 percent of the time — and when Hispanic drivers were stopped, there were illegal substances only 27 percent of the time the dogs alerted, suggesting that police were profiling Latinos.

Then there’s civil forfeiture, a process by which law enforcement can confiscate people’s assets if they believe they are involved in illegal activity — taking the house of a suspected drug dealer, for example, or taking cash from a car if a dog indicates that the car or the money itself has drug odors attached to it, even if no drugs are found. Money can be seized even if there are never any charges or conviction, and citizens usually have to pass through a grueling and complicated court process to get their assets returned.

A spotlight has been pointed on forfeiture abuses in recent years, and momentum has started to pick up in curbing them. In January, outgoing Attorney General Eric Holder limited the ability for local and state police forces to seize assets using federal law as an excuse. But forfeiture remains an important source of funding for local departments and district attorney’s offices, providing motivation for police to grab as much money as they can. An example came to light when two Nevada State Troopers sued their department and the Las Vegas police department in 2012, claiming that officers deliberately cued their dogs to alert to vehicles the handlers thought were suspicious in order to seize cash from the passengers.

That’s why one-time certification isn’t sufficient to trust that sniffer dogs are doing an honest job, Shoebotham argues.

“Trial court consideration of detection-dog field performance records as part of the court’s canine-reliability determination is an essential firewall to preventing police use of marginal, or even unreliable, drug-detection dogs,” the law professor wrote.

The legalization of marijuana makes the certificates even less appropriate. For dogs that have been extinction trained, the certificate gives no proof whatsoever that the training is effective over time.

“If you have a certification, that is a benchmark for a certain point of time,” Shoebotham said to Reset. “It’s critically important to have training records to show that this is a behavior that this animal has been able to stop demonstrating over the long term.”

States that have legalized recreational use of marijuana are taking a patchwork approach to their dog policies. Service dogs are expensive, costing $10,000 or more apiece, plus additional thousands for ongoing training, so it’s not an easy task to just replace all the dogs that alert to marijuana.

In Larimer County, Colorado, the sheriff’s office said it was keeping its dogs, but would no longer use a sniff as probable cause to search a vehicle. Denver and its suburbs said they weren’t making changes to their K9 program. However, the Colorado District Attorneys’ Council instructed police that a dog alerting to marijuana no longer gives them probable cause.

Dogs aren’t required by the Criminal Justice Training Commission in Washington state to alert for pot anymore, but the group will still certify dogs that do. Most jurisdictions simply won’t get new dogs trained to marijuana so they will eventually switch over through attrition, but in the meantime, Seattle police and others in the state are providing extinction training to their dogs. Some localities, like Tacoma, decided to keep their dogs on marijuana alert, since it’s still illegal in certain circumstances, like possession of more than one ounce.

The Washington Association of Prosecuting Attorneys put out a memo in 2012 stating that dogs still trained to alert to marijuana can raise questions about a search warrant but are “not fatal to a determination of probable cause.” The officers would have to provide additional evidence that a crime was being committed, such as the words of the suspects or visible evidence of other illegal substances.

Oregon is also taking a jurisdiction-by-jurisdiction approach as to how they deal with their canines.

“This is a conversation every agency with a drug detection dog is having or has had for several months now and how it’s being addressed varies from agency to agency,” Daren Kendrick, president of the Oregon Police Canine Association, told the Oregonian. “But police work is like the ocean, we have to go with the flow and always be able to adapt to changing technologies and laws to help the community.”

Alaska, meanwhile, looks like it’s putting all its marijuana-smelling dogs out of work and replacing them.

The Pacific Northwest Police Dog Association, which provides dog services including extinction training in Washington, Oregon, Alaska and other states, did not respond to multiple requests for comment. The Scientific Working Group on Dog and Orthogonal detector Guidelines, which establishes best practices for dogs and detection teams, also did not respond to several interview requests.

Several lawyers contacted by Reset who deal with marijuana cases in Colorado and Washington said they haven’t heard yet of people getting wrapped up by a supposedly extinction-trained dog. With luck, all the service dogs originally trained to marijuana will retire before it becomes an issue, but the problem could pop up again and again as more states legalize it.

Questions about the extinction training pile on growing doubts about sniffer dogs’ reliability in general. There’s no question that dogs have extraordinary noses and can identify the odors of various substances — the issue is that they can alert for numerous other reasons, and their handlers have no way of telling what motivated the dog to give its signal.

“Dogs do not alert to the drugs themselves, they alert to odors emitted by the drugs,” says James Woodford, a chemistry PhD who in the 1980s identified and patented the methyl benzoate odor that is used to train dogs to find cocaine. “When it strikes, nobody knows anything about what it’s striking on.” Notably, he points out, the odor the dogs use to identify heroin, acetic acid, is found in many substances, including secretions from the human body.

Sometimes, the dogs alert when there are no illegal substances at all. A study led by former dog handler Lisa Lit at the University of California Davis found that 18 dogs trained to sniff drugs and explosives falsely alerted over 200 times, and only had a 14.5 percent success rate overall. “It isn’t just about how sensitive a dog’s nose is or how well-trained a dog is,” Lit said of the study. “There are cognitive factors affecting the interaction between a dog and a handler that can impact the dog’s performance.” In effect, the dogs pick up on their handlers’ cues — when the handler believes there is contraband, the dog knows, and alerts.

“The idea of the infallible dog is a creature of legal fiction. It’s recognized that the science doesn’t really measure up to the level of credibility that we give a dog for the purposes of drug seizures or drug searches,” says says Nick Morrow, retired L.A. County deputy sheriff and speaker for Law Enforcement Against Prohibition. “When there’s an alert on a vehicle, you don’t know what substance they are alerted to, when it got there, who put it there.”

But if there are any questions about the dog’s reliability, it becomes the handler’s word against anyone else’s. There’s no way to prove that the dog alerted falsely — if no illegal substances are found, officers can always claim there must be residual odors somewhere in the vehicle. If you’re driving with nothing but legal marijuana in your car, and an extinction-trained dog gives an alert, you could be out of luck — and cash.

“You can manufacture probable cause just by pointing your dog in the right direction,” Morrow says. “The drug dog doesn’t know what drugs look like, doesn’t care, doesn’t know anything about the Constitution and won’t testify against a less than honest handler so the secret’s safe if there’s a shady act going on.”