Blood alcohol content

Blood Alcohol Content, often abbreviated BAC, is the concentration of alcohol in blood, measured in [[percent] by volume. It is used as an objective (and ideally therefore, legally uncontestable) measure of the level of impairment of an individual, especially as it pertains to the operation of a motor vehicle.

Different countries define different levels of BAC to be acceptable. Some coutries, eg Sweden allow only zero BAC for the legal driving of a motor vehicle.

In the United States, most states define inebriation by law at a specific BAC (often about 0.10 %). The federal government is forcing a change to 0.08%. In some states, underage drunken drivers are considered legally impaired at lower levels (perhaps 0.02%).

In Australia, the limit is 0.05% in most states and territories, and either 0.02% or zero for inexperienced drivers (learner drivers or those on probationary licenses). It is enforced by random breath testing.