Police in Colorado Can't Search Cars Just Because They Smell Like Weed

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Drug-sniffing dogs in Colorado might soon be out of a job — or at least must be retrained to detect illegal drugs that aren’t weed.

Colorado’s Court of Appeals ruled that police don’t have enough probable cause to search a car without the owner’s permission if a drug-sniffing dog trained to smell marijuana and other drugs is used to detect the scent.

K-9 unit dogs typically can’t differentiate between what drugs they are smelling. Since weed is recreationally legal for adults over 21 in Colorado, a drug-sniffing dog could smell weed inside a car and cops could find another illegal substance in their search.


A case that resulted in a man’s arrest for possessing a pipe “commonly used to smoke meth” and possessing a controlled substance produced the ruling.

The Coloradan reports:

The decision came out of a 2015 case in Moffat County, where a drug-sniffing dog named Kilo alerted officers to the presence of an illegal drug in a truck driven by Craig resident Kevin McKnight, The (Grand Junction) Sentinel reported.

But because Kilo could not tell officers whether he smelled pot or other drugs, the search was illegal, judges wrote. The dog was trained to identify to detect cocaine, heroin, Esctasy, methamphetamine and marijuana. Marijuana possession by adults over 21 is legal in Colorado. 


It’s unclear how K-9 units would go about training dogs to stop detecting the now-legal drug. But the three-panel group of judges wrote in their decision that a drug-sniffing dog trained to smell weed could theoretically violate Coloradans’ privacy.

“A dog sniff could result in an alert with respect to something for which, under Colorado law, a person has a legitimate expectation of privacy, i.e., the possession of one ounce or less of marijuana for personal use,” the ruling read.


The panel concluded that police “lacked the requisite reasonable suspicion to subject McKnight’s truck to a dog sniff.” Their ruling set a legal precedent for future search cases involving dogs trained to smell weed and warrantless searches. McKnight’s conviction was also overturned.

Obviously, the decision doesn’t mean Colorado drivers can just roll around smoking weed in their cars all the time. However, if a driver in Colorado happens to be driving with less (or more) than an ounce of pot in the car and is breaking no other laws, police officers can’t legally search his or her car based on a drug-sniffing dog’s detection alone.