You’re stopped for a DUI late at night. You’ve had a few beers. After the officer questions you, and instructs you to perform coordination exercises that he calls “field sobriety tests,” he asks you to submit to a chemical test. What can you do?

In California, a condition of retaining your driver’s license is that you agree to take a chemical test if requested to by a peace officer. If you refuse to take a chemical test (either a breath test or blood test), your license will be suspended. On a first DUI, the suspension will be for a year.

In addition to the driver’s license suspension, there could be a forced blood draw. The officer could get a phlebotomist to draw blood from you against your will.

A recent Supreme Court decision clarifies whether a search warrant is necessary before a police officer can force a blood draw. In Missouri v. McNeely, in a majority opinion written by Justice Sotomayor, the Court held that the police officer must obtain a warrant from a judge before performing the blood draw if there is reasonable time to do so. If you have a current DUI case, in which blood was drawn against your will, talk to your lawyer. It is likely that the blood was taken without a search warrant and that McNeely gives you a legal defense.