All 50 states have adopted implied consent laws requiring motorists as a condition of driving in the state to consent to a blood alcohol content (BAC) test if they are suspected of drunk-driving.
The Supreme Court will decide whether state statutes criminalizing a person’s refusal to take a chemical BAC test where police have not obtained a warrant are unconstitutional. Thirteen states criminalize the refusal to take a warrantless BAC test.
In Missouri v. McNeely (2013) the Supreme Court held that police generally have to obtain a warrant to conduct a BAC. So the argument goes, it is unconstitutional to criminalize the refusal to take a BAC test if a warrant was required to conduct the test but not obtained.
The three decisions that the Supreme Court has agreed to review all upheld the state statutes.