The legal limit for blood alcohol concentration (BAC), as you have been told since your first driver’s ed class, is .08%. If you hit that level or go over it, the court assumes you had enough to drink that it impaired your ability to drive. There are a few ways to get a BAC reading, but the most common is to use a breath test at the police station.

If they assume that you are impaired at .08%, does that mean that they assume you are sober — or at least not impaired — at .07%? Does having a low BAC protect you from getting a DWI?

It does not. The court simply doesn’t get to assume impairment, but they can still find that you were impaired. The officer may have given you field sobriety tests that you failed, for instance, or you may have exhibited clear signs of impaired driving, like causing an accident. You can still face DWI charges even if your breath test results show that you are under the limit.

In some cases, police officers will also argue that you were over the limit when you were driving. Maybe you caused a crash at a remote location, for instance, and it took two hours to get a BAC reading. If it was .07% after those two hours, they can assume that it was over the legal limit when the accident took place, knowing how fast your body breaks down alcohol.

If you do wind up facing DWI charges in Texas, you need to know all of your defense options.