@squinney,
to be boring for a moment, it all depends on the blood alcohol level when you drive. And that depends on how much you have drunk, and over what period of time the body has to metabolise the alcohol. As you are drinking beer, the body is also burning off the calories it contains.
The trouble is this balance depends on the individual. But its possible that if you drink quite a large amount of beer over a long period of time you might be fit to drive, whereas if you gulped down a couple of whiskeys (particularly with soda water which aids adsorption into the blood stream) and then got in the car, you could be taking a very severe risk.
It actually infuriates me that the law states the blood alcohol limit must not exceed 80mg/100ml or in breath 35microgrammes/100ml...WHEN NO ONE REALLY KNOWS WHAT THAT MEANS IN SIMPLE TERMS OF HOW MUCH CAN I DRINK.
There is a speedometer in my car and if I'm doing 50 mph in a 30 zone, I know I'm breaking the law. But the govt here has discouraged the sale of "alchometers" on the grounds that it would encourage people to drink up to the limit and then drive. They want people NOT TO DRINK AND DRIVE AT ALL. But its not illegal to drink and drive. Its only illegal to drink too much and drive. As a responsible citizen I want to know how much that is (one mass or two!!) to which I get no intelligible answer.
It would be far better to make drinking and driving illegal, that is reduce the limit to such a level that the driver knows for sure that if he has even one alcoholic drink, he is breaking the law. The limit could not be zero, to account for alcohol based medication....and of course communion wine
but it would at least give a clear message to drivers.
sorry about all that but i feel quite strongly about this issue, having found myself once very slightly on the wrong side of the limit with pretty disastrous consequences.