There no easy way of knowing because it depends on too many things like your body weight and metabolism. If you want to stay legally safe stick to a half. I'm a skinny fucker and I'll have a cheeky pint, but I always let it sit for at least an hour before I go, and I know I'd still probably be fucked if I got pulled and breathalysed.
Just treat it the same way you would if you were transporting loads of drugs, remember the golden rule- Make sure you're not breaking any laws except the one you intend to. Check your lights before you set off, and drive like it's your driving test, but go just a tiny bit over the speed limit so you don't look like someone who'd trying to avoid suspicion.
>>89467 Surely there is number for less urgent calls? Just call your local rozzer HQ and report him and his license plate. Dispatch will send a car out looking for him.