Former Prosecutor Serving Minnesota And Wisconsin Since 1992

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How to challenge chemical breath test evidence

On Behalf of | Apr 12, 2022 | DWI/Drunk Driving

Breathalyzer tests lead to many drunk driving charges each year. Because of how serious the penalties and consequences associated with DWI charges can be, it is helpful for accused drivers to be familiar with how they can challenge a breathalyzer test should the need arise.


Breathalyzer tests may not always produce reliable results and those facing drunk driving charges based on them should know that. Breathalyzer tests are used in many drunk driving situations and are a significant component of the criminal justice system. Breathalyzer tests lead to many criminal charges which can result in steep penalties and consequences for accused drivers.

Tests thrown out

In two different states, greater than 30,000 breathalyzer tests were thrown out recently over a 12-month period. Concerns over reliability largely due to relaxed government oversight and human error led to the tests being tossed out. Thousands of other tests have also been invalidated across the country in recent years. Breathalyzer tests must be properly calibrated and in some situations when they were not, they yielded results that were as much as 40% too high.

User error

Maintaining breathalyzer tests is left to police departments that may lack the resources to properly do so or lack the expertise needed to maintain them. They may also have low standards that lead to improper maintenance of breathalyzer tests. When breathalyzer tests are not properly maintained and calibrated, they may yield unreliable results that can lead to unreliable drunk driving charges. Accused drivers should understand when this is the situation and know what to do about it. Criminal defense protections may be able to help them in these cases.