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Breath test results are usually strong evidence, but not always

On Behalf of | Mar 22, 2023 | Criminal Defense, DUI/DWI

Prosecutors in Pennsylvania and around the country usually rely on breath test results to prove that a motorist accused of driving while under the influence was behind the wheel with a blood alcohol concentration of 0.08% or higher. The machines used to conduct breath tests at police stations are extremely sophisticated and accurate, and their use is supported by solid science. However, they only provide accurate BAC readings when they are properly maintained and regularly recalibrated, and many police departments fail to perform these basic tasks.

Breath test evidence thrown out

This was the conclusion reached by journalists in 2019 when they investigated breath-testing procedures in the United States. It was also the opinion of a Massachusetts judge who threw out 30,000 tests after determining that no law enforcement agency in the state was conducting toxicology tests properly. In New Jersey, 18,000 breath tests were excluded because a state trooper had not been properly trained to use a breath-testing machine. If you are arrested for drunk driving in Pennsylvania, your criminal defense strategy should include asking to see the maintenance records of the machine that was used to conduct your breath test to verify that proper protocols were followed.

Illegal traffic stops

Breath test results cannot be used in court if drunk driving arrests are made after illegal traffic stops. Police officers can only pull cars over if they have good reason to do so, and any evidence they discover during a traffic stop is inadmissible under the fruit of the poisonous tree doctrine if they acted without the requisite reasonable suspicion at the outset. Traffic stops are only legal if police officers witness a motor vehicle violation, receive a report about a vehicle that may have been involved in a crime or have probable cause to believe that the occupant or occupants of a vehicle have committed a crime, are committing a crime or plan to commit a crime.

Evidence is not always as strong as it appears

Drunk driving suspects often plead guilty because they believe the evidence against them is overwhelming. Breath test results and police reports are usually enough to establish guilt in DUI cases, but they may be challenged if police officers acted improperly or sophisticated machinery was not properly maintained.