The Supreme Court is considering whether or not police officers should be able to force a suspected drunk driver to take a breathalyzer test or have blood drawn at a hospital. Judges are split on whether compelling someone to take one of these tests counts as an “unreasonable search,” as prohibited by the Fourth Amendment. Prosecutors in the test case argue that police need to act quickly because alcohol in the body rapidly disappears from the blood—but lawyers for the American Civil Liberties Union say that police officers should have to obtain a search warrant before they can make someone take a test. It all started when a Missouri highway patrol officer stopped a driver named Tyler McNeely for speeding. The officer said McNeely smelled of alcohol, slurred his speech and failed roadside sobriety tests. But he refused to provide a breath sample—so the officer brought him to the hospital and forced him to give a blood sample. McNeely’s blood alcohol level was 0.154, nearly double the legal limit of .08%. But in March, the Missouri Supreme Court threw out that blood test evidence, saying that the police must obtain a warrant first. The US Supreme Court is expected to rule on the case in January.