You go to Las Vegas with your spouse, and the two of you spend a lot of time walking around on The Strip. You hit up casinos, watch the crowds, eat a delicious dinner and have a few drinks. It’s a nice evening out, and then you head back to your rental car to drive out to your AirBnB for the night.

Since the last thing you did was eat dinner, you don’t feel drunk. You did not have that many drinks, and you were out all evening. You know that you’re not 100% sober, but you also feel like you’re definitely under 0.08% for BAC (blood alcohol concentration) and you know that’s the legal limit. You hop in the car and start driving out of town.

While you do, you get pulled over. A police officer tells you that you ran a stop sign; you never even saw it. He then asks you if you’ve been drinking and gives you a breath test when you admit that you have. You blow a 0.07%.

At first, you feel thrilled; you’re not over the legal limit, just like you thought. Doesn’t that mean you didn’t break the law and you won’t get arrested? But then the officer arrests you anyway, and you have no idea what is happening.

The misconception

It’s a common misconception that the only way to get a DUI is to go over the legal limit. That’s not actually how it works.

The reality is that the police can arrest you if you have been drinking and it has impaired your ability to drive. This means that you can get a DUI at 0.07% or 0.06%, for instance, if the officer can show that you were driving while impaired.

Remember, you ran the stop sign. The officer may have noticed other signs, like delayed reactions or slurred speech, when he talked to you. Based on all of that, he can potentially make a DUI arrest, no matter what your BAC is on the breath test.

So why use breath tests?

When people find out how this works, they often wonder why we use breath tests at all. What is the point of the legal limit?

It’s simple. The legal limit means that going over 0.08% is proof enough that you are impaired by the alcohol. The officer does not need anything else. If you’re under 0.08%, you may or may not be impaired. The officer needs something else, beyond the breath test, to prove it.

Your rights

These misconceptions can lead to arrests when people don’t know they broke the law. If this happens to you, it’s time to learn more about your legal rights.