The detection of drivers whose ability to drive is impaired by alcohol is a difficult task. Readily available information regarding the blood alcohol concentration of a suspected impaired driver should assist in the detection process. While relatively crude devices designed to determine specific blood alcohol concentrations have been available for some time, a new generation of sophisticated electronic breath alcohol measuring devices recently became commercially available.

The Parliament of Canada has provided legislation which permits the use of certain roadside screening devices. Some provinces now employ this technique. Detailed experience in the use of the Alcohol Level Evaluation Roadside Tester (ALERT) in Alberta is examined in this paper.

Data showing the change in type and frequency of alcohol related driving charges in areas using ALERTS is presented. The effect of roadside screening technique on the average blood alcohol concentration of detected impaired drivers is discussed. Evidence is offered which purports to show that the use of roadside screening devices will assist the police to detect impaired drivers at a lower blood alcohol concentration than previously encountered. Literature references are supplied.