You only have one drink at dinner, and you actually forget to finish it because you’re in such an engaging conversation. As the meal wraps up, you quickly drink the rest and walk out to your car.
Pulling out of the parking lot, you get stopped by a police officer. They give you a breath test. You can’t believe it, but the test says that your blood alcohol content (BAC) is over the legal limit. What happened?
Deep lung air vs. mouth air
The problem may be that portable breath tests are supposed to measure deep lung air. This is how the device determines what your blood alcohol concentration (BAC) is without actually testing your blood.
The device doesn’t know what air it is getting, though. Your “mouth air” could still contain a fair amount of alcohol because you literally just finished your drink. It has definitely not had time to get to your bloodstream and impair your driving — and you may not even be impaired after a single drink — but the sensor detects it in the mouth. It’s virtually undiluted, and it can provide a very high BAC reading, even in a situation where a blood test would show just trace amounts of alcohol.
What if you get arrested for a DUI?
All of the above may be true, but the officer doesn’t know when you last drank or how much you had. They may arrest you anyway, and then you need to know what legal steps to take. Make sure you stay calm and cooperate, even if you feel that the arrest is unfair.