Reduction in the legal blood alcohol limit from 0.08 to 0.05: effects on drink driving and alcohol related crashes in Adelaide

Abstract

The legal blood alcohol limit for drivers in South Australia was lowered from 0.08 to 0.05 g/100mL on 1 July 1991. The effects of this change on late night drink driving were assessed in the Adelaide metropolitan area by reviewing the results of a series of roadside breath alcohol surveys and by a comparison of the rate of alcohol involvement in crashes over a 15 year period. There was a short lived reduction in the percentage of late night drivers with a blood alcohol level at or above 0.08 at about the time of the introduction of random breath testing by the police in the early 1980s. This has been followed by a steady downward trend in this percentage from the mid 1980s. The blood alcohol levels of fatally injured drivers, as measured by the above criterion, have followed a similar downward trend to that observed in the roadside surveys. However, there have been negligible changes in the distribution of drivers' blood alcohol levels above 0.08 in the fatally injured group and in accident-involved drivers who were breath tested at the scene by the police. There was no marked change in the downward trend in the percentage at or above 0.08 in any of these groups of drivers following the reduction in the legal blood alcohol limit. This does not necessarily mean that the change in the legal limit had no effect because the reasons for the continuing decrease in both drink driving and the involvement of alcohol in crashes since the mid to late 1980s are far from clear.