Random Stopping for DUI

An approach to finding impaired drivers is random stopping and assessment of every driver using the road at times and locations where drinking and driving is common. In this procedure, drivers are stopped at random and the officer conducts a brief interview at the driver's window to determine whether there is evidence of drinking. If such evidence is detected, the driver is invited out of the vehicle for further observation.

In the USA, the Fourth Amendment to the US Constitution precludes random stopping except in structured checkpoint operations. However, even in such operations, the Fourth Amendment is currently interpreted as precluding mandatory breath testing of all individuals stopped. Therefore, a behavioral element is a part of the decision-making process at American checkpoint operations.

The first step in the measurement process involves a brief interview of the driver in his/her vehicle, during which an officer makes an initial determination as to whether the driver is likely to be impaired. Once an initial determination has been made that the driver may be impaired through an interview at the driver's window, the officer will ask the driver to take a few field sobriety tests. For decades, police have used a variety of performance tests to assess the degree of impairment for drivers suspected of alcohol-impaired driving. The admissibility of these tests as evidence relied entirely upon court acceptance of their validity as indices of inability to drive safely.