On the night of February 3, 2015, Kevin McKnight was driving around in his pickup truck when the police stopped him.[1] Ostensibly, they pulled him over for turning without using his turn signal, but the real reason was more complicated.[2] The officer who pulled McKnight over had been following McKnight’s pickup truck for at least fifteen minutes; he had seen the truck idle outside the site of a recent drug bust,[3] and the officer recognized the woman riding shotgun as a “user of methamphetamine.”[4]  Once he had pulled over McKnight, the officer called the county sheriff’s office to request a drug-sniffing dog.[5] The dog, Kilo, was trained to detect the odors of cocaine, ecstasy, methamphetamine, heroin, and marijuana.[6] When Kilo arrived on the scene, he alerted the police that he detected one of these substances.[7] McKnight denied that he had any drugs in his possession, but after Kilo more thoroughly sniffed around the truck, the police found a pipe containing meth residue under the back seat.[8] McKnight was charged and convicted of possession of a controlled substance.[9] On appeal, McKnight challenged the trial court’s denial of his motion to suppress the evidence obtained during the police’s roadside search of his truck. McKnght argued that Kilo’s sniff search violated the Colorado state constitution, as it infringed on his legitimate expectation of privacy.[10]

In most states, McKnight’s appeal would have failed instantly. In 2005, the Supreme Court held in Illinois v. Caballes that because there is no legitimate privacy interest in possessing illegal drugs, a drug dog sniff is not an unconstitutional search.[11] However, McKnight was arrested and convicted in Colorado, a state where recreational marijuana use has been legal since 2012. When Kilo alerted the police to a drug odor in McKnight’s car, the dog could have simply detected marijuana, which McKnight had a legal right to possess in certain quantities.[12] Thus, Kilo’s sniff alone could not give rise to the reasonable suspicion of a crime required to search McKnight’s truck.[13]

The Colorado Court of Appeals agreed with McKnight’s argument. Because “[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 . . . that dog sniff should now be considered a ‘search’” under the Colorado constitution.[14] Accordingly, McKnight’s conviction was reversed.[15]

The implications of People v. McKnight may ripple across the country. Since the adoption of Colorado’s Amendment 64 legalizing marijuana, six other states and the District of Columbia have legalized either recreational or medicinal use of marijuana. The trend is clear, and states with blanket prohibitions of marijuana possession may soon be in the minority. Dogs like Kilo, who may bark when he smells heroin or a legal amount of marijuana may need to be retrained or else retired.

The Colorado court’s decision demonstrates that as the legal regulation of marijuana changes, traditional drug policing techniques will have to change as well. Indeed, the new rule announced in People v. McKnight—that a drug dog sniff alone is not sufficient grounds to conduct a warrantless search—will probably make it harder for police to enforce laws prohibiting marijuana possession above a certain amount. Drug-sniffing dogs can’t be trained only to alert law enforcement to certain amounts of marijuana. But decreasing the number of overall marijuana arrests—which are costly and associated with “staggering racial bias”—may not be a bad thing. The court in People v. McKnight should be applauded for reminding the police that as drug laws change and possession rights expand, the police’s approaches to investigation and enforcement must change as well.




[1] People v. McKnight, 2017COA93, 2017 WL 2981808 at *1 (Colo App. July 13, 2017).

[2] Opening Brief for Defendant-Appellant at 2, People v. McKnight, 2017COA95, 2017 WL 2981808 (Colo. App. July 13, 2017), 2016CA50.

[3] McKnight, 2017 WL 2981808 at *1.

[4] Id. at *2.

[5] Opening Brief for Defendant-Appellant at 3.

[6] McKnight, 2017 WL 2981808 at *2.

[7] Id. at *2.

[8] Opening Brief for Defendant-Appellant at 4.

[9] McKnight, 2017 WL 2981808 at *1.

[10] Opening Brief for Defendant-Appellant at 5.

[11] See 543 U.S. 405 (2005).

[12] McKnight, 2017 WL 2981808 at *3.

[13] Id.

[14] Id.

[15] Id. at *1.