What Are Potential Ways to Challenge a Breathalyzer Test?

Categories: DUI Defense

A woman driving under influence.

Driving under the influence (DUI) in Colorado is a serious offense. Even if this is your first DUI conviction, you could face from five days to one year in jail, a fine of $600 to $1,000, and between 48 and 96 hours of community service. In addition, first-time DUI convictions carry a driver’s license suspension of nine months. In other words, if an officer arrests you for DUI in Colorado, your life is likely to change for at least the next full year. But an arrest is not the end of the story. In fact, after an arrest is when an experienced DUI defense attorney can become a game-changer. Why? Because DUI arrests typically (if not always) involve a Breathalyzer test. And those tests are fallible, which means that the results can be challenged in court.

Challenging Breathalyzer Test Results

Police officers commonly use Breathalyzer tests to measure blood alcohol content (BAC) if they suspect someone is driving under the influence. Law enforcement relies on these machines, but they are not infallible. How often are breathalyzers wrong? The truth is, no one really knows. What we do know is that they can provide inaccurate results. And if the law punishes even one innocent person based on a faulty test reading, that is one too many.

Critics allege that Breathalyzer tests can have a margin of error of up to 50% compared to blood tests that measure alcohol content from the same person. That large margin of error can result in wrongful convictions if test results go unchallenged. So if you think your Breathalyzer test results were wrong, it is time to contact an experienced DUI defense lawyer. It takes experience to know how to challenge your results successfully. But when you have good legal representation, there are several ways to challenge the test.

Lack of Probable Cause

Before addressing Breathalyzer fallibility, it is important to know that officers must have probable cause to pull you over in the first place. Police are not allowed to stop drivers randomly. They must reasonably suspect you of breaking the law in some way. If an officer pulls you over without probable cause, then any evidence they get from you after the stop is not admissible in court. This includes the result of any field sobriety test or breath test.

Improper Testing Procedures

The Breathalyzer machine is a scientific instrument that must be used correctly to get an accurate reading. The officer performing the test must be certified, meaning that the police department trained them to give the test properly. They must accurately instruct you on how and when to blow into the machine and must be able to correct any missteps that occur as you perform the test. Any improper instructions or mistakes in the execution of the test may result in a faulty reading.

Here are some additional legal requirements of DUI breath testing in Colorado:

  • The subject must provide two valid samples of equal size;
  • These samples must be within .02 of each other, and the court will use the lower of the two readings;
  • Deep-end air from the lungs on the exhale must make up the sample;
  • The test must be immediately preceded by a 20-minute period where the subject does not eat, drink, belch, throw up, or introduce any foreign object into the mouth;
  • The administrator must provide a clean mouthpiece for each test subject;
  • The administrator must continuously observe the subject throughout the testing period; and
  •  The administrator must provide their signature confirming that they fulfilled all legal requirements of the test.

If any of these steps are missed or mishandled, you can challenge the results.


After you consume alcohol, your blood alcohol content continues to rise significantly for a period of time afterward. Because of this, it is imperative that an officer administer the Breathalyzer test within two hours of when you last drove. In other words, if the officer waits too long to test you, your blood alcohol content (BAC) may continue to rise after you are no longer driving. This increased BAC may not accurately reflect your BAC while you were behind the wheel. So if more than two hours elapsed between getting pulled over and your test, your lawyer may be able to challenge the results.

Improper Calibration

Breathalyzer machines are sensitive. As such, it is critical that they are routinely inspected and calibrated. In other words, professionals must check the device at regular intervals. Its measurements must be compared to a known sample to ensure that it is providing accurate results. If any evidence exists that the machine used for your test was not properly maintained and calibrated, then the results can be questioned and possibly thrown out entirely.

Your Physical Condition Can Skew Results

Perhaps surprisingly, there are a number of physical conditions that can skew Breathalyzer test results. Among these are:

  • Gastronomic disorders like gastroesophageal reflux disease (GERD);
  • Dental work or dental adhesives that can trap alcohol in the mouth;
  • A high-protein, high-fat diet that leads to increased ketone levels;
  • Having a high fever;
  • Hypoglycemia; and
  • Working in a profession with exposure to high levels of acetone, like as a nail technician or painter.

Any of these physical conditions may cause a false reading on a Breathalyzer test.

Certain Medications

Several medications can cause a false reading on a Breathalyzer test, including:

  • Asthma medications such as albuterol, salmeterol, and budesonide;
  • Oral pain relievers like Anbesol that contain 60% alcohol;
  • Nyquil and certain other Vicks products that contain alcohol, and
  • Mouthwash or breath sprays that contain alcohol.

Any of these and other oral items like chewing gum can produce flawed results on a breath test.

We’re Here to Fight for You!

The attorney at Mark S. Rubinstein, P.C., know that a DUI conviction can have a devastating effect on your life. Our highly experienced DUI defense legal team is ready to challenge every aspect of your DUI arrest to make sure that your rights are protected. So if you have been arrested for DUI, give our office a call or contact us online today.

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.