Results from breathalyzer tests are often the primary evidence presented in DWI cases. A failed breathalyzer test indicates that your blood alcohol level (BAC) is .08, which means that you are legally intoxicated, thereby allowing law enforcement to arrest you and charge you with DWI.
Challenging the reliability of the test you received could be your best defense against a DWI charge. Here’s how you can go about challenging the test.
Work with your lawyer on the best defense strategy for your situation. Common strategies involving breathalyzer defense include:
- No search warrant
- Improper training or qualification for the person administering the test
- Lack of probable cause for drunk driving
- Too much elapsed time between the last drink, the time driving and when the sample was taken
- Little or no observation time prior to the test
Challenging the Accuracy of the Machine
Some lawyers mount successful DWI defenses based on the accuracy of the breathalyzer machine. These challenges are particularly successful if the reading shows that the driver was at or just above the legal limit. Scientific studies have shown that breathalyzers can produce false positive results if a driver has been around alcoholic fumes.
Improper calibration of the machine is another issue. Your lawyer can ask when the machine was last calibrated and whether there have ever been any issues with the machine in the past that could affect the accuracy of the results.
The process of test administration can also affect the outcome of a breathalyzer test. For example, your DWI defense lawyer can ask about the specific procedures for the machine used and whether there were any deviations from the manufacturer’s recommendation.
Your lawyer can also cite a number of other factors to discredit the accuracy of a breathalyzer test. These include your own physical activity prior to the test, the chemical composition of your body and atmospheric pressure. Respiratory issues and hyperventilating can also affect the accuracy of results.
Tell your lawyer about any medical conditions that you may have as some are known to produce alcohol-like compounds that could be mistaken for heavy drinking. Another commonly used item, mouthwash containing alcohol, has also been known to result in false positive breathalyzer tests if the mouthwash was used within a few hours of the test.
Other Legal Challenges
Depending on the jurisdiction where the alleged DWI occurred, law enforcement officers must be given informed consent from the driver before a test can occur. Failing to follow this procedure can result in a judge throwing out the results of a breathalyzer test.
Not having reasonable suspicion to pull a driver over is also a sound argument to request that the results of a breathalyzer test be thrown out. The arresting officer must testify that the driver was driving erratically or otherwise breaking a traffic law.
The absence of probable cause, such as slurred speech or an odor of alcohol, is also a legal violation and can negate the breathalyzer results. Finally, if the arresting officer doesn’t show up at the trial or if two officers arrested you and the one administering the test doesn’t show, it is a violation of your constitutional rights.