The report examines the results of random breath testing and assesses psychological factors influencing drunken driving. Methodological weaknesses are evident in existing evaluative studies. Although enforcement of relatively stiff Swedish sanctions appears to have a greater effect on deterring drunken driving than control of beverage sales, sceptics argue that there is little statistical support for or against a particular kind of sanction or level of severity in its application. Statistical analysis of random breath tests authorized by 1975 legislation indicate that the largest group of detected drunken drivers are above 30 years of age have high blood alcohol concentrations (BAC), and have a serious drinking problem. The next largest group consists of young drivers with lower BAC's but with heavy alcohol consumption. In order to redress the failure of Swedish policy toward young drivers and older drivers with serious drinking problems, drunken driving like general alcohol consumption, must be viewed as a public health issue. The perceived risk of police detection, one of the most important psychological factors influencing the incidence of drunken driving, is low in Sweden, and about the same after as before the introduction of random breath tests. It is recommended that police use the concept of selective enforcement, or optimal enforcement of drunken driving laws for selected periods of time, to significantly influence drunken driving. Ten references are provided.