Drug-sniffing dogs are set off by their handlers. https://www.npr.org/2017/11/20/563889510/preventing-police-bias-when-handling-dogs-that-bite https://www.npr.

Drug-sniffing dogs are set off by their handlers. https://www.npr.org/2017/11/20/563889510/preventing-police-bias-when-handling-dogs-that-bite https://www.npr.org/2017/11/20/563889510/preventing-police-b... > some cops jokingly refer to the dogs as "probable cause on four legs. > And there are powerful incentives not to change how things are done, says Andy Falco, a former police K9 handler who now trains dogs and works as an expert witness for defense attorneys. > "All [police departments] care about is how many cars you're pulling over, how much money is being seized because your dog alerted," he says, referring to departments that use civil asset forfeiture to keep money and other property found in cars after a K9 alerts to the scent of drugs. > "They go, 'It's easy! All I gotta do is walk my dog around, and look for him to change his behavior slightly, and then we can go inside and sometimes we'll find a million dollars and then we can seize it!'" > "There's been cars that my dog's hit on... and just because there wasn't a product in it, doesn't mean the dog can't smell it," says Gunnar Fulmer, a K9 officer