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Challenging breath test results in a DUI case

On Behalf of | Mar 20, 2023 | Criminal Defense

When prosecutors in North Dakota are assigned drunk driving cases, breath test results are usually their most important pieces of evidence. The devices police officers use to conduct breath tests are extremely sophisticated and accurate, which is why few people who are charged with DUI challenge the results they provide. However, these machines only function properly when they are carefully maintained and regularly recalibrated. When they are neglected, breath tests results may be unreliable and inadmissible in court.

A widespread problem

When breath-testing equipment is not regularly recalibrated or properly maintained, it can be an issue that affects and entire police department or several police departments. Widespread problems with breath tests were discovered in Massachusetts and New Jersey in 2019. In New Jersey, a calibration error led to more than 18,000 tests being invalidated. In Massachusetts, a judge threw out eight years’ worth of breath tests because of systemic problems with testing procedures and maintenance.

Probable cause

Breath test results could also be ruled inadmissible in a drunk driving case if the police officer who conducted the test acted without probable cause or stopped the vehicle involved illegally. Police officers cannot act on hunches alone. They can only pull a car over if they observe a traffic violation or reasonably believe that a crime has been or is being committed, and they may only order breath tests when they observe clear signs of intoxication. When rights protected by the Fourth Amendment may have been violated, criminal defense attorneys may seek to have DUI charges dismissed.

Science and human error

The science supporting breath testing is strong, but the machines used to conduct tests are not always reliable. When breath tests results are challenged successfully, it is usually because a police officer or technician made a mistake or took a shortcut.