Skip navigation
CLN bookstore

Colorado Supreme Court Announces Sniff by Drug Dog Trained to Detect Marijuana Now Constitutes a ‘Search’ Requiring Probable Cause

by Dale Chappell

Now that marijuana is legal in several states, does a sniff by a drug dog trained to detect marijuana (and other drugs) constitute a “search,” since it can now reveal something that is lawful to possess (small amounts of marijuana)? The Supreme Court of Colorado ruled that it is and that police now need probable cause to use such a drug dog in order to justify a search.

When cops saw Kevin McKnight’s truck parked in front of a known drug house, they followed it and, when he made an illegal turn, pulled it over and called in a drug-sniffing dog. The dog promptly altered to the driver’s door, and cops found a methamphetamine pipe under the back seat in their subsequent search. McKnight was later convicted of various drug charges. On appeal, the court of appeals reversed McKnight’s conviction, finding that probable cause was needed to use the drug dog now that marijuana is legal. The Colorado Supreme Court granted the State’s petition for a writ of certiorari and affirmed the court of appeals’ ruling.

In an opinion that could help open the door for challenges to drug dog sniffs in states where marijuana is now legal, the Court ruled that because marijuana is no longer “contraband,” a dog sniff, which had not been deemed a search because it was used to detect only contraband, now constitutes a “search” that requires probable cause to use the drug dog.

In Illinois v. Caballes, 543 U.S. 405 (2005), the U.S. Supreme Court held that a dog sniff isn’t a search because the dog was trained to detect only contraband, and a person doesn’t have a legitimate privacy interest in possessing contraband. Therefore, the Caballes Court reasoned, a dog sniff isn’t a “search.” In People v. Esparza, 272 P.3d 367 (Colo. 2012), the Colorado Supreme Court adopted the holding in Caballes.

However, in 2012, Colorado voters passed Amendment 64, which legalized possession of an ounce or less of marijuana by those age 21 or older. Of note, since Colorado legalized marijuana, nine other states and the District of Columbia have followed suit. “Marijuana is now treated like guns, alcohol, and tobacco,” the Court noted. “While possession of these items is lawful under some circumstances, it remains unlawful under others.”

This rationale led the Court to overturn its holding in Esparza. “An exploratory sniff of a car from a dog trained to alert to a substance that may be lawfully possessed violates a person’s reasonable expectation of privacy in lawfully possessing that item,” the Court explained. “Because there was no way to know whether [the drug dog] was alerting to lawful marijuana or unlawful contraband, [it] violated McKnight’s reasonable expectation of privacy,” constituting a search, the Court concluded.

Because the drug dog’s sniff is now considered a “search,” probable cause is needed. Probable cause exists when the facts known to an officer “would warrant a person of reasonable caution in the belief that contraband or evidence of a crime is present,” the Court reiterated. This means more than a “reasonable suspicion,” the Court made clear, further distancing itself from its decision in Esparza.

In the present case, the Court found that there was no probable cause for the dog-sniff search. The fact that McKnight’s truck was parked near a drug house did not give rise to probable cause, even coupled with the illegal turn afterward that justified the traffic stop. “Drug users have the same constitutional rights as everyone else,” the Court instructed.

But what about the dog’s alert and the discovery of the methamphetamine pipe and the fact that cops didn’t find any marijuana? “We don’t measure a search’s constitutionality by looking at what it reveals,” the Court said. Rather, a court must examine the constitutionality of the search itself based on what was known at the time of the search. The search here was illegal, regardless of what was eventually found, the Court concluded.

Accordingly, the Colorado Supreme Court upheld the court of appeals’ ruling that the evidence must be excluded and reversed McKnight’s conviction. See: People v. McKnight, 2019 CO 36 (2019). 


Subscribe today

Already a subscriber? Login

Related legal case

People v. McKnight


Federal Prison Handbook


Disciplinary Self-Help Litigation Manual


Advertise here