You may be aware that the results of Breathalyzer tests can be used as evidence in a drunk driving case. However, you may have also heard that many thousands of test results have been determined to be inadmissible.

Improper calibration, use by a law enforcement officer who wasn’t properly trained and other issues can bring the blood alcohol content (BAC) level they’re designed to determine into question. However, not every Breathalyzer device result can or should be thrown out.

A ruling from one Colorado appeals court

For example, in 2020, an appellate court in Colorado ruled that a defendant didn’t have the right to challenge the functionality certificate of an Intoxilyzer 9000 that was used during a traffic stop. The man, who had three prior DUI convictions, was found guilty of felony driving while ability impaired (DWAI) when his BAC registered over .06%. Although the device produced a document certifying that it was in working order at the time of the stop, the defendant argued that the document wasn’t signed, as required under the law.

The appellate judges determined that with no evidence that the device wasn’t working properly, there was no reason to believe that the result wasn’t accurate. They also noted that the certificate didn’t qualify as testimony, so the defendant didn’t have a constitutional right under the Confrontation Clause of the Sixth Amendment to “confront” it as a person would have the right to confront a witness.

It could be argued that while having a person sign every functionality certificate would be too burdensome, the lack of a signature can still call into question whether the device was actually functional.

What is open to challenge in a DUI case?

There are many things that a defendant might be able to challenge in a DUI case. While this particular defendant also challenged the constitutionality of the stop, the court ruled that the fact that his car had some nonfunctional lights made the stop valid.

The best way to determine what your options are for challenging any part of a drunk driving or any other case against you is by having sound legal guidance.