Russell Hebets Feb. 25, 2014

If anyone has been investigated for suspicion of Driving Under the Influence, or knows someone who has, you probably have heard of the police administering a breath test on the side of the road. After questioning you on the amount of alcohol you have had, the officer will typically ask you if you are willing to give a breath sample to determine if you are safe to drive. He or she will then pull out a hand-held device and ask you to blow into it. The device is called a Preliminary Breath Test or PBT, and it is bad news. If you take nothing else from this article, take this: Don’t Cooperate with the PBT.

Results from a PBT are extremely imprecise and are not scientifically reliable. The contraption is so imprecise that the Colorado legislature specifically excluded the admission of any test results in a trial and similarly excluded and information indicating that a defendant refused to take the Preliminary Breath Test. C.R.S. 42-4-1301(6)(i)(III). That’s right, they can’t use your refusal to comply with a PBT against you. However, police can use a PBT to compile probable cause to arrest you. They can do this despite the fact that the PBT is based on imprecise science.

Let’s say you just used mouthwash, or took some cold medicine, or very recently had a single drink. The Preliminary Breath Test does not have a way to detect mouth alcohol, so there is a good chance your results will say you are hammered regardless of your actual level of sobriety. The police will believe the results and you’ll find yourself with a one-way ticket to the drunk tank.

Let’s be clear. The PBT is very different from the Intoxylizer test that is administered at the police station. This test, while still problematic, is much more reliable than the PBT. Refusal to take a breath or blood test also has driver’s license repercussions which are not at play with refusal to comply with a roadside PBT. Here’s the bottom line: The police can use PBT results to say you’re drunk, but can’t do anything if you refuse to give them that evidence. So let’s not let them use bad science to throw you in jail for DUI.