Abstract
The authors examine the suggestion that drink driving offences are reduced when new legislation is introduced but gradually return to former levels. The theory is applied to the impact of the introduction of the Administrative Driver's Licence Suspension in Ontario. Details are given of the monthly surveys carried out before and after the measure was introduced. The results show a high level of public awareness at the time of introduction. The impact on self-reported drinking appears consistent with a beneficial effect of the law but is not as clear as the impact on knowledge.