Answer: Most commonly, a police officer in a drunk driving case, if they want to do a blood test, they will begin by asking if you will consent or if you will agree to take a blood test. So if you agree to take a blood test, then they don’t need a warrant because you agreed to it. If you do not agree to it, first you might face some penalties because you did not agree to it—such as license revocation—but, if you refuse to take the test and the officer still wants to do the blood test then, yes, the officer does need to get a warrant.
Most counties in Wisconsin have a process where the police officer can get a warrant, very quickly, even in the middle of the night. Usually it involves speaking with a judge over the phone and they have some sort of fill-in-the-blank warrant, they fill it out, they get the judge to agree to it and then they can get a blood sample. It typically takes an hour or less for them to do that.
Now, just because the police get a warrant doesn’t mean that everything is fine. If you have a drunk driving case where a warrant was obtained, it’s very important to have a knowledgeable attorney review the warrant, the warrant application and look at all the surrounding circumstances to find out whether the warrant was valid and whether the blood test was properly done.