Credit: Library of CongressIn 2013 the U.S. Supreme Court held that police officers in Missouri violated the Fourth Amendment when they obtained a warrantless and nonconsensual blood sample from a man suspected of drunk driving. “In those drunk-driving investigations where police officers can reasonably obtain a warrant before a blood sample can be drawn without significantly undermining the efficacy of the search,” Justice Sonia Sotomayor wrote for the majority in Missouri v. McNeely, “the Fourth Amendment mandates that they do so.”
It was a significant defeat for law enforcement. But Justice Sotomayor also poined out that it was not a total defeat. “States have a broad range of legal tools to enforce their drunk-driving laws and to secure BAC [blood alcohol concentration] evidence without undertaking warrantless nonconsensual blood draws,” she observed. “For example, all 50 states have adopted implied consent laws that require motorists, as a condition of operating a motor vehicle within the State, to consent to BAC testing if they are arrested or otherwise detained on suspicion of a drunk-driving offense.”
But that observation by Sotomayor also raised some constitutional questions of its own. For instance, what if a state makes it a crime for a suspected drunk driver to refuse to submit to a warrantless blood test? Does the Fourth Amendment offer any protection to the refuseniks?