A reasonable expectation of privacy is one of the most fundamental rights people hold in a free society. Accordingly, the Fourth Amendment prohibits warrantless searches, with few exceptions. Police officers in Wisconsin violated that right when they drew Gerald Mitchell’s blood while he was unconscious—to test his blood alcohol content after a drunk-driving arrest. The state has attempted to excuse the officers by citing an implied-consent statute, which provides that simply driving on state roads constitutes consent to such searches.

The right to privacy is not absolute; police are allowed to search for evidence of a crime. But in doing so, they must follow procedures that comport with the Constitution. Before police conduct a search, Johnson v. United States (1948) indicates that the evidence should be judged by “a neutral and detached magistrate instead of being judged by the officer engaged in the often competitive enterprise of ferreting out crime.” The Fourth Amendment contains a simple requirement for law enforcement that is an effective bulwark against unreasonable searches: get a warrant first.

Unfortunately for Mitchell, the Wisconsin Supreme Court upheld this unconstitutional search under the “pervasively regulated business” exception, which allows for warrantless administrative inspections of certain highly regulated businesses. But this exception is quite narrow and designed to ensure regulatory compliance, not to facilitate evidence-gathering in cases of suspected of criminal activity.

The U.S. Supreme Court has only recognized four types of business to which the exception applies: liquor sales, firearms dealing, running an automobile junkyard, and mining. None of these resemble the simple act of driving a vehicle. The state court thus erroneously conflated the licensing of a driver with a highly regulated business order to justify an otherwise unreasonable search.

Gerald Mitchell is thus asking the U.S. Supreme Court to overturn the Wisconsin Supreme Court and find that this warrantless, non-consensual search violated his Fourth Amendment rights. Cato has joined the Rutherford Institute in filing an amicus brief in support of his petition. We argue for the basic notion that unconscious people can’t consent to anything, especially police searches, and that inspecting a coal mine for safety compliance—a justified exception to warrantless searches—is not the same as searching a driver’s blood in an attempt to convict him of DUI.