['To determine whether the use of a passive alcohol sensor (PAS) in routine traffic enforcement increases the driving-under-the-influence (DUI) arrest rate of alcohol-impaired drivers.', 'Officers in a Maryland police department were randomly assigned to one of two groups: the first with PAS devices and the second without PAS devices (the control group). Then, the PAS units were switched from the first to the second group. Arrest, PAS, and preliminary breath-test data were collected on 714 nighttime traffic stops over two enforcement periods.', 'The DUI arrest rate for the officers with and without the PAS was the same, 13%. Officers who made no arrests without the PAS benefited the most from using it. Drivers stopped for an unsafe lane change, driving over the center line, and negligent driving were arrested for DUI 35% of the time.'] Does a note on the use of passive alcohol sensors during routine traffic stop?