5 Police Mistakes That Can Be Key to Your DUI Defense

Even if police do pull you over for a lawful reason, such as for a traffic violation, that doesn’t mean that they can start asking you about whether you’ve been drinking or testing you for suspicion of drunk driving. Once the officer has completed his or her purpose for the stop, he or she can't legally continue to detain you unless the officer has a reasonable suspicion that you have engaged in additional criminal activity, such as driving under the influence.

If police stopped you and administered tests without a reasonable suspicion that you were driving under the influence, everything that happens after, including the results of any breath, blood, or chemical test, could be excluded from evidence.

Police officers can’t pull you over without a lawful reason. That lawful reason can be a traffic violation or driving that creates a reasonable suspicion that you may be impaired. If an officer pulls you over without a lawful reason, your attorney can argue that any evidence obtained after the illegal stop – such as field sobriety or breath test results – were improperly obtained and should be excluded from evidence, and that the charges should be dismissed insofar as they were the direct result of a constitutionally prohibited stop.

If an officer suspects that you are impaired, he or she may ask you to perform field sobriety tests (FSTs) to evaluate your condition. These tests are highly subjective and if they are administered incorrectly, they can create an impression of impairment even in someone stone cold sober. Your lawyer can challenge the ways the FSTs were conducted and how the officer interpreted the results.

Breathalyzers and other devices used to test for blood alcohol content, especially those administered during a stop, are famously unreliable and often inaccurate. Even the slightest problem with the maintenance and calibration of the device, the way the test is administered, and other, external factors can taint the reliability of the test and turn a legal 0.07% into an illegal 0.08% BAC.

A skilled DUI defense attorney can attack this crucial piece of the prosecution’s evidence as being so unreliable it should not be used as evidence because of reasons such as:

• The timing of the test
• Insufficient qualifications and training of the test administrator
• Poor maintenance, calibration, and testing of the equipment
• Failure to follow required test procedures
• Incorrect mixing of testing chemicals
• Device or test sample contamination
• Independent factors that may impact blood alcohol readings such as existing “mouth alcohol,” acid reflux, diet, and breathing patterns.

You’ve seen enough TV shows and movies to know that when police arrest you, they need to advise you that you have the right to remain silent, that anything you say can and will be used against you, you have the right to an attorney, and so on. If you have been arrested for DUI, the officer must advise you of your constitutional rights before they begin conducting a “custodial interrogation” and asking you questions. If you make any incriminating admissions or statements under questioning, those statements can be excluded from evidence if the officer failed to advise you of your Miranda rights beforehand.