This fall, the Supreme Court of the United States will hear oral arguments in a case that challenges the use of drug-sniffing dogs to perform warrantless searches outside a suspect’s house. The case, Florida v. Jardines, arose when Miami police received a tip that Joelis Jardines was growing marijuana in his home. The police took a drug-sniffing dog around the perimeter of his house, and the dog indicated that it smelled drugs. Based on that information, the police obtained a search warrant of the house, and they found marijuana plants growing inside.

The Supreme Court has previously allowed drug-sniffing dogs to be used around cars or in the airport, but since that time a study from UC Davis has called into question the validity of drug-sniffing dogs. UC Davis recruited 18 law enforcement dogs with their human handlers for the study. Experimenters told the handlers that drugs or explosives might be present at the testing site, but neither one was present in any of the rooms. If the dogs had behaved appropriately, they would have passed through all four rooms without alerting their handlers. Only one of the 18 dogs did not falsely alert in any of the rooms.

UC Davis researchers hypothesized that the dogs were taking cues from their handlers. If that is true, the dogs are merely relaying the preconceptions of their handlers, and it calls into question the validity of drug-sniffing dogs in any circumstance.

The Supreme Court might not speak on the validity of drug-sniffing dogs when it rules on this case, but it should. It is important that police have actual evidence when they request that a search warrant from a judge; the preconceptions of dog handlers should not be enough for probable cause.