"What Good Is A Pot-Sniffing Dog When Pot Is Legal?"

The question in the title of this post is the headline of this new Jacob Sullum commentary at Forbes. Here are excerpts:

Drug dogs typically are trained to detect marijuana and several other substances. When they smell one of those drugs, they are supposed to alert their handlers with a signal such as barking, scratching, or sitting down. But the dogs cannot indicate which drug they have smelled, let alone distinguish different quantities—a crucial issue in Colorado, Washington, Oregon, and Alaska, where adults 21 or older are allowed (or soon will be allowed) to possess up to an ounce of marijuana in public.

Until recently, those canine limitations did not matter, because any quantity of marijuana was unambiguously illegal throughout the country. But the ongoing collapse of marijuana prohibition is undermining the legal assumptions that have made drug-detecting dogs such a handy law enforcement tool, one that can be deployed at will to justify searches that would otherwise be unconstitutional.

According to the Supreme Court, letting a police dog sniff a suitcase or a car is not a search, so it does not require probable cause. At the same time, an alert by that dog provides probable cause for a search. Those conclusions, which have always been questionable because they are based on a grossly exaggerated sense of the average police dog’s accuracy, look even shakier in light of marijuana legalization....

Washington State Patrol and the Seattle Police Department [have] decided to phase out the use of marijuana-trained dogs, gradually replacing them with animals that alert only to heroin, methamphetamine, crack, and cocaine powder. Police in some Oregon jurisdictions, including Clackamas County and Medford, also are moving away from marijuana-trained dogs....

The Tacoma Police Department is sticking with conventionally trained dogs, and so are police in several Colorado cities, including Denver, Aurora, Lakewood, Pueblo, and Colorado Springs. New dogs are expensive (about $15,000 each if fully trained, according to the Colorado Springs Gazette), and these departments say the old ones are still useful in certain situations, such as school searches, or in conjunction with other sources of evidence.

Some cops say they are waiting for guidance from state courts. “There are so many unanswered questions,” the officer in charge of K-9 training at the Colorado Springs Police Department told Bloomberg News. “There have not been any test cases to say yes or no, we do not have the right to do this.”

Other departments are being more proactive. The Gazette reports that Loveland, a city about 50 miles north of Denver, is phasing out its marijuana-detecting dogs based on advice from the Larimer County District Attorney’s Office. “It basically goes back to the Fourth Amendment prohibition on illegal searches,” a police spokesman told the paper. “We want to make sure we aren’t infringing on people’s rights.”