The U-S Supreme Court is considering whether police can order a blood test for drunken driving suspects without a warrant.
The court was clearly divided in oral arguments Wednesday.
The court is considering the appeal of Tyler McNeely, who was stopped two years ago for speeding in Missouri.
Police say he failed field sobriety tests, refused to take a breathalyzer test, and was given a blood test without a warrant, despite his objections.
State courts were subsequently divided over whether the test could be admitted as evidence, prompting the Supreme Court appeal.