Dr. Declan Bedford:

Alcohol impairs driving. I was involved in research in my department years ago. We carried out research on men. We asked men why they did not drink and drive and why they obeyed the rules of the road. The only reason they did not drink and drive was the fear of getting caught. It was not because they did not think it was a bad idea to drink and drive. The main deterrent was the fear of getting caught. My view, and the view of my colleagues, on that was that what was required was highly visible enforcement in order that people felt there was a chance of getting caught and that the penalty had to be high enough to ensure people would not want to get caught. We need highly visible enforcement of what we have got. We should see how that works and after that, reducing the limit would be good. Men have told us that highly visible enforcement is required, and international evidence shows that it works as well. At the same time we have a 20 mg limit now for professional drivers and people like that, which is basically a level of zero. However, nothing works if people have a perception that they are not going to get caught.