The legal limit for blood alcohol content for Australian motorists, lowered from 0.08% in the early 90's.
This excludes those on a probationary licence, who are not legally permitted to drive whilst having a blood alcohol level above .00%, with the exception of Western Australian probationary licence holders, who are permitted 0.02% BAC.
The whole situation with having one's blood alcohol content measured by a breathalyser is quite problematic in that there are so many legal loopholes that unless you are quite exceedingly drunk, it's not hard to 'get out of it'.
Personally I never drive when I've been drinking at all, mostly because I am still on a probationary licence, but knowing the following may help you one day if you are forced to drive after drinking due to some emergency and are pulled over by the police. Do not take this as a licence to drive drunk, or I will visit you and whup your butt.
If your breathalyser result is close to .05, or the police believe you to be acting as if you are affected by alcohol, they are entitled to have you wait 20 minutes before taking another test, to see if your BAC is increasing or decreasing. If you still read over the limit you are entitled to a blood test. You are also entitled to have your personal physician perform this blood test if you wish. By the time your personal physician is called out, your liver should have done its job, and your BAC should be rather lower than it was originally. If you are still over the limit, you very much deserve to go straight to hell and be repeatedly run over by SUV's.
If you are involved a major accident (one in which more than $2000 worth of property is damaged, or in which someone is injured) the police are required to be called out and will breathalyse all drivers involved. If you have been drinking, you may be worried about this and try to leave the scene of the accident. This is illegal. The only circumstance under which it is legal to leave the scene of a major accident before the police arrive is if you believe you are in need of medical attention. Do with that loophole what you wish.
I only know this info to be accurate in Western Australia. I am not certain of how much of this applies in other states of Australia or other countries in the world, but I imagine some of it would apply to varying degrees.