Probability of arrest while driving under the influence of alcohol

Summary The probability of arrest while driving at a blood alcohol level over 0.10% was 0.0058 (about one in 200). There is considerable interest in defining the relationship between the probability of being arrested for driving under the influence of intoxicants (DUI) and blood alcohol concentration (BAC)*. Such information, if accurately known, could be put to a variety of uses, including public information, police patrol management information, DUI patrol evaluation, and estimation of the number of drunken drivers on the road. In surveys associated with the Alcohol Safety Action Projects (ASAP), thousands of persons have been interviewed and asked, among other questions, what they thought their chances were of being stopped by the police after having had too much to drink. The object of such a question is to measure the level of public awareness of enforcement of the DUI laws. Even those who pose the question do not know the answer, however; and such a question has no single answer unless the level of intoxication, or BAC, is specified. There have been no detailed studies to establish such probabilities. Previous estimates suggest that the probability of being arrested while staking a 10 mile trip with a BAC above 0.10% is about 0.0015†.1 Accurate knowledge of the probabilities of being arrested for DUI is necessary if a public education campaign against drunken driving is to retain the trust and confidence of the public. This kind of knowledge could also prove to be a valuable police patrol management tool. The officer in charge of DUI patrols would have a standard against which to measure the performance of his unit. In addition, if the probability of arrest for DUI under specific patrol conditions can be established with confidence, it should be possible—by patrolling a particular area and obtaining …