How “Preliminary Breath Tests” Work in Colorado DUI Cases

Categories: Criminal Defense

Vail DUI Lawyer

Like most states, Colorado takes DUI cases very seriously. This makes sense, as all of us benefit when our roads are safe from drunk drivers. However, the methods that law enforcement uses to ensure that our roads are safe sometimes curtail our individual best interests. In other words, in the pursuit of drunk drivers, police sometimes make mistakes – and those mistakes can be costly. So how do you protect yourself from these mistakes, and will taking the preliminary breath test when you’ve been stopped for DUI help you or hurt you?

What Happens at a DUI Stop?

A man at a DUI stop being tested by a cop.Whenever a person is pulled over for suspected DUI, there is a series of things that happen. Typically, the officer will ask for your license and registration, followed by a series of questions. They will ask you things like where you’ve been, or if you’ve had anything to drink tonight. Do not be fooled by the seemingly casual nature of these requests. They are designed to give the officer ammunition from which to arrest you.

So while you are required by law to give the officers your identification and supply your name, you are really not required to do much else. You will be asked to do quite a bit, but you are not required to. So what is the smart move?


The officer will obviously ask you for your name and ID. By law, you must provide your name and ID to the officer. But while you are looking for these items, the officer typically fires a few questions at you. They ask you to both speak and search for your ID for two reasons:

  • Because they need to know your name and they need to see your ID, and
  • To see if you can handle speaking to them intelligently and searching for documents at the same time.

So know that, as you search your glove compartment, you are being watched and evaluated. If you seem to get confused or disoriented and can’t hold a conversation with the officer, this will be an indication to him or her that you are under the influence of an intoxicating substance.

Have you been drinking tonight?
There is only one reason that the officer is asking you this question, and that is to gather evidence against you. Once you have been pulled over, the officer already suspects you of DUI. What they are looking for now is confirmation.

Here’s the problem. No matter what you answer, it isn’t going to help you. Saying no when other indications of intoxication are present will indicate that you are lying, and saying the typical “only one or two beers” does nothing but give the officers confirmation that yes, you have been drinking. So unless you truly have not been near alcohol all day, the best course of action is to very politely decline to answer.

Do not be combative or rude. And do not refuse to speak entirely, as you must assert your right to remain silent. Say something very polite like, “I will not be answering that question officer, I’m choosing to remain silent.”

Where have you been tonight?
With this question, law enforcement is again looking for information they can use against you. You do not have to help them make their case by feeding them facts and statements that can later be used against you. And you should NEVER lie. The safest course of action is the assertion of your right to remain silent. Once again, a simple but polite phrase should be enough to make the officer move on.


At some point during the DUI stop, the officer will likely ask you to step outside of your vehicle to perform some field sobriety exercises (FSE). This subject is an article unto itself, but suffice it to say that it is usually not in your best interest to perform such tests. You are not required to, and there are no direct consequences for refusal. These tests are based on questionable science and are difficult for most people to perform perfectly, even under ideal conditions. So trying to perform them perfectly under the stress of a potential arrest is futile for most. Again, a simple “I choose not to submit to field sobriety exercises” should do.

Preliminary Breath Test

DUI checkpoint and breathalyzerNow comes the request for the preliminary breath test. This is a handheld device that is used to measure your blood alcohol level in the field. However, this test is not nearly as accurate as the breathalyzers used at the station. But because an arrest must be made before a breathalyzer is administered, officers will ask you to submit to the preliminary test to help them decide whether or not to arrest you.

However, officers take the totality of the circumstances into consideration when determining whether or not to make an arrest. If they have already observed several indicators of intoxication, chances are that taking the preliminary test and scoring low will not dissuade most officers from arresting you. They know the test is inaccurate and will usually trust their own observations over the test.

So in trying to determine whether or not to take the preliminary breath test, you must again ask yourself what is to be gained by submitting. If you have not had any alcohol all day, then taking the test may save you from being arrested. However, if you have had any alcohol at all, the test’s inaccuracies may not bend in your favor. Again, it’s better not to serve up evidence for the prosecution, so politely declining is likely in your best interest.

Arrested for DUI? Let Us Help

If you or a loved one has been arrested for DUI in Colorado, it is critical that you speak with a trusted attorney at Mark S. Rubinstein, P.C. who will aggressively fight for your rights. Having a lawyer by your side can help get a far better outcome for your case and can make sure that your rights are fully protected. Call us today for a free consultation, or fill out our online contact form. We look forward to helping you.

Mark Rubinstein

Attorney Mark S. Rubinstein has been practicing law for more than 30 years, including 25 years in Colorado. He founded Mark S. Rubinstein, P.C., in Carbondale after working for law firms in Denver and earlier in his career in San Diego. He focuses his practice in the areas of criminal defense and personal injury representation, and he is well known throughout western Colorado as an effective and unwavering advocate for his clients.