An analysis of alcohol breath tests results with portable and desktop breath testers as surrogates of blood alcohol levels

► Portable and desktop breath tests can be valid measures of alcohol impairment for evidentiary purposes. ► Their cutoff levels can be set relative to their accuracy to minimize their rates of false alarms (false positives) relative to blood alcohol levels. ► A statistical decision tree model is proposed for setting the cutoff levels for the two commonly used breath testers relative to the most common BAC thresholds: 50 mg/dl and 80 mg/dl.