he only safe amount to drink when driving is....none.

And to only drive when you are in perfect health? And not distracted by emotional issues? And not under pressure from work?

I understand the sentiment but to single out alcohol as the only cause of driving impairment just comes across as wrong to me. Given that the introduction and dispersal of alcohol to and from the system is very quantifyable (see this article) I think some leeway can be built in.

For any of the other issues I mention, and many more, there is no way to quantify it the effects and I feel, therefore, that people are just taking the easy option of blaming alcohol. Doing this masks the real problem that some people should just not be driving whether thay have had a drink or not!

Cheers

DeG