Drunk driving law by country

The laws of driving under the influence vary between countries. One difference is the acceptable limit of blood alcohol content before a person is charged with a crime.

The Criminal Law Amendment Act, 1968–69 made it a per se offence to drive with a BAC in excess of 80 mg/100 ml of blood. Refusal of a police officer's demand to provide a breath sample was made an offence at the same time and both began as summary conviction offences, with a mandatory minimum $50 fine.

Some states now have two statutory offenses. The first is the traditional offense, variously called driving under the influence of alcohol (DUI), driving while intoxicated/impaired (DWI),operating under the influence (OUI), or operating while intoxicated/impaired (OWI). The second and more recent is the so-called illegal per se offense of driving with a blood alcohol concentration (BAC) by volume (mass of alcohol/volume of blood) of 0.08% (previously 0.10%) or higher. In most states, the timing of the chemical test is important because the law mandates a result within a given time period after the driving stopped, usually two hours. The first offense requires proof of intoxication, although evidence of BAC is admissible as rebuttably presumptive evidence of that intoxication; the second requires only proof of BAC at the time of being in physical control of a motor vehicle. An accused may be convicted of both offenses, but may only be punished for one. The differences between state penalties still varies. Wisconsin, for instance, is the only state that continues to treat first offense drunk driving arrests as forfeiture.

Some states also include a lesser charge of driving with a BAC of 0.05%; other states limit this offense to drivers under the age of 21. All states and DC also now have zero tolerance laws: the license of anyone under 21 driving with any detectable alcohol in their bloodstream (BAC limits of 0.01% or 0.02% apply in some states, such as Florida.) will be suspended. In 2009, Puerto Rico joined these states, setting a limit of 0.02 for drivers under 21, despite maintaining a legal drinking age of 18.

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