Part of a post from Ian Tyrrell:
 
By the way,on the Drink Driving controversy, note that New
South Wales and some other Australian states have .05 and RANDOM roadside
breath tests. Generally, the road toll has been cut significantly in recent
years, though other factors such as the level of economic activity and
current cmapaigns against speeding are also possible causes. The .05 rule
means real changes in how people drink, and I believe it has encouraged
either more moderate drinking, or using designated drivers. No doubt Robin
Room would know much more about any research, and I speak here merely as an
observer. You can post this if you think it useful.