Briefs and amicus briefs are being filed in a Supreme Court case that could have a major impact on Fourth Amendment jurisprudence in order to resolve a major mess. The question in Florida v. Jardines is whether a police officer can use a drug sniffing dog at someone’s door to determine if there is contraband inside the home. The mess is a result of the tension between the Supreme Court’s holdings, the reality of using drug sniffing dogs, and our intuitions about privacy.
First, the Supreme Court has held that, when performed in a minimally invasive way, like at an airport or outside one’s car, the use of a drug detection dog is not considered a “search” that implicates the Fourth Amendment or requires any suspicion. This is largely due to the fact that the use of drug sniffing dogs is considered a “binary search,” which either detects or fails to detect the presence of contraband. Because the Court has held in no uncertain terms that we have no legitimate expectation of privacy in contraband (I’m not as certain about this proposition when considering the history and purpose of the Fourth Amendment), a device or dog that detects only whether contraband is present or absent does not invade any expectations of privacy.
However, as Professor Leslie Shoebotham’s amici curiae brief (detailed on EvidenceProf blog) argues, drug sniffing dogs often detect the presence of molecular compounds found in both contraband and innocent items, such as vinegar or soap. Another way of framing this is that drug sniffing dogs are not binary because of their tendency to false positive. And there we have Mess Number 1: the Supreme Court’s drug sniffing dog jurisprudence is based on the false idea that the use of a drug sniffing dog is not a search because it detects only the presence or absence of contraband. It is unlikely that the Supreme Court in Jardines will reverse its firmly established position that the use of drug sniffing dogs is not a search. Instead, the Court will likely rely on the holding that a dog binarily alerts or does not alert to the presence of contraband, but will treat as a separate question whether a dog is accurate enough in its alert to give the police probable cause to obtain a warrant and conduct a full search of the home.
Thus, Mess Number 1 is more easily resolved than Mess Number 2, which concerns our intuition. It FEELS wrong for the police to march up to random homes and sniff doors with a drug detection dog. Yet, if the use of a drug detection dog does not actually infringe upon privacy rights or require any suspicion, that’s exactly what could happen. How is the Supreme Court going to distinguish a car or a suitcase from a house if the use of a dog is not a search at all?