If a police officer pulls your car over and requests that you submit to a Breathalyzer® test, can you say no? The answer is, well, yes and no.

You can always refuse to take a breath test, and no one can force you to do it. (Unless you happen to be unconscious. More on that in a moment.) But the consequences of refusal can be dire. In Florida, your first refusal can result in automatic suspension of your driver’s license for a year. Subsequent refusals are considered a misdemeanor offense and bring an 18-month suspension. Plus, your refusal is admissible in court as evidence against you if you are charged with driving under the influence (DUI). Ironically, in our legal system, exercising your right to remain silent cannot be used against you in court; but keeping your mouth shut when told to breathe into a tube — that is fair game.

How can that be? It is all due to a little trick of the law called implied consent. Under the 4th Amendment protection against unreasonable searches, law enforcement is only permitted to search your person, your vehicle, or your home if they have one of two things: your consent, or probable cause (i.e., a good reason to believe you are breaking the law).

Acknowledging that breathalyzer and other blood alcohol tests constitute a search of your person, all 50 states have established implied consent laws, which state that by accepting a driver’s license, you are automatically consenting to such a search when a police officer requests it. (In Florida, this is actually printed right on your license). Withdrawing your consent puts you in violation of the terms under which your license was issued, thus allowing the motor vehicle department to take it back as a matter of administrative (not judicial) procedure.

A person who is unconscious, of course, cannot refuse the test; therefore, law enforcement may rely on implied consent to administer a blood test with no further ado.