A motorist stopped on suspicion of driving under the influence of alcohol might consent to a breath test with results that show a high BAC content. 

Is this accurate? An incident in Philadelphia shows that machines are not infallible and breath test results can affect DUI cases in unexpected ways. 

Police department surprise

In the summer of 2016, a private attorney caught the Philadelphia Police Department off guard with the information that the calibration dates had expired on their Breathalyzer machines. The police removed all the machines immediately and sent them out for recalibration. 

New solution needed 

Calibrations must take place on an annual basis. Updating the machines involved replacing the essential solution that ensures the accuracy of blood alcohol content readings. Once filled with the fresh solution, the machines were back in operation in various locations around the Philadelphia area the same day. 

Inadmissible evidence

Because of the calibration error, the police department asked the district attorney to review DUI cases involving breath tests for the first half of the year in order “to determine the future of those cases.” Since the machines contained expired solution, defense attorneys could say that the results were inadmissible in court, a stance that had the potential of altering the outcome of up to 1,000 cases from January to June. 

Possible errors

Building a successful defense for a driver arrested on suspicion of DUI requires careful investigation of the facts, including whether there were possible administrative errors or equipment malfunctions. As the Philadelphia Breathalyzer incident illustrates, an unusual circumstance can lead to an unexpected outcome.