Breath test results in New Jersey, presented as evidence supporting more than 20,000 convictions, have been ruled inadmissible by the New Jersey Supreme Court. The Alcotest-brand breath tests, which according to the court were generally admissible if properly used, require calibration every six months. The police officer formerly responsible for calibrating the tests across five New Jersey counties was charged two years ago with falsifying records because he wrongfully certified he followed proper calibration procedure.

The officer was supposed to measure the temperature of a “simulator solution” with a thermometer to ensure that the solution matched body temperature. The testing of the simulator solution quantifies the level of measurement uncertainty present in the device, meaning, the calibration gives a numerical range for how far away the results of the breath test might be from the real Breath Alcohol Concentration of the tested individual.  Since the state calibration is the only non-manufacturer produced check on the devices, an expert witness testified about the necessity of calibration stating that, without proper calibration, “if [the manufacturer] accidently [sic] used the wrong temperature in calibrating the calibration units and the probes, then the temperature variance would go undetected and the Alcotest’s readings would be factually inaccurate.”

Nick Corasaniti and Sharon Otterman of the New York Times wrote an article further explaining the ramifications of this decision, available at https://www.nytimes.com/2018/11/13/nyregion/nj-dwi-convictions-court.html. The decision itself is available at https://www.njcourts.gov/attorneys/assets/opinions/supreme/a_58_16.pdf?cacheID=8cZDnut.