In People v. McKnight a police dog named Kilo, trained to alert to marijuana as well as methamphetamine, cocaine, heroin and MDMA, barked at a pickup in Craig, and officers found a pipe with methamphetamine residue. Because adults in Colorado may lawfully carry an ounce of marijuana, the Colorado Supreme Court held that such a dog "can no longer be said to detect 'only' contraband": its sniff is a search that needs probable cause, and the conviction was overturned. Reason noted that police would have to retrain such dogs to ignore marijuana or replace them.[1]
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References
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