Florida v. Harris, 568 U.S. 237 (2013), was a case in which the United States Supreme Court addressed the reliability of a dog sniff by a detection dog trained to identify narcotics, under the specific context of whether law enforcement's assertions that the dog is trained or certified is sufficient to establish probable cause for a search of a vehicle under the Fourth Amendment to the United States Constitution. Harris was the first Supreme Court case to challenge the dog's reliability, backed by data that asserts that on average, up to 80% of a dog's alerts are wrong. Twenty-four U.S. States, the federal government, and two U.S. territories filed briefs in support of Florida as amici curiae.

A detection dog or sniffer dog is a dog that is trained to use its senses to detect substances such as explosives, illegal drugs, wildlife scat, currency, blood, and contraband electronics such as illicit mobile phones. The sense most used by detection dogs is smell. Hunting dogs that search for game, and search and rescue dogs that work to find missing humans are generally not considered detection dogs but fit instead under their own categories. There is some overlap, as in the case of cadaver dogs, trained to search for human remains.