Swiftness of punishment for drivers impaired by alcohol is likely to be increased objectively by administrative license revocation laws. These laws provide that a driver who fails or refuses a breath‐alcohol test has his license confiscated on the spot by police, with formal loss of driving privileges following shortly thereafter. This study of New Mexico law looks for evidence of a deterrent impact of administrative license revocation. Interrupted time‐series analysis finds a permanent drop in the proportion of driver and pedestrian fatalities involving the presence of alcohol precisely at the time that the law went into effect. However, lack of publicity for the law and the existence of a complex procedure, unpopular with many police, appear to have diminished the law's effectiven