Blood alcohol concentration limits

Should young drivers have a zero blood alcohol limit?

Research has shown than driving after drinking alcohol can increase the risk of crashing by up to 11 times.  The more alcohol consumed, the greater the risk of crash.  Australia research has shown that, compared to more experienced drivers (those who have been driving for 5 years or more), first-year Provisional drivers are three times more likely to be injured in a crash if they have been drinking.  New Zealand research also found a greater risk for young drivers: drivers in their 20s had more than 5 times the risk of crashing compared to drivers in their 30s for all blood alcohol concentrations (BACs); even as low as 0.02% (0.02 g/100ml).  Risk of crashing further increased if the driver was driving at night, or with passengers.

Support for restrictions

Early introduction of a 0.05% blood alcohol limit for all drivers has been highly successful in reducing alcohol crashes and related injuries.  At the time of introduction, 0.05% was found to be the level at which the risk of crash doubled.  Given that inexperienced young drivers have an even greater level of risk, a “zero tolerance” approach has since been adopted in restrictions for Learners and Provisional drivers.  All Australian States and Territories currently have a zero (0.00 g/100ml) blood alcohol concentration (BAC) limit for these drivers with the exception of the Australian Capital Territory, where a 0.02% BAC limit applies.

Zero alcohol restrictions for young drivers have reduced crash-related fatal crashes and injuries considerably.  An Australian study compared young drivers involved in serious crashes locally and in the United States.  The study collected information from Queensland, Tasmania, Victoria, Western Australia, Maine, Maryland, and Massachusetts, which allowed comparison of crashes across a range of different BAC limits (0.00%, 0.002%, 0.04%, 0.05% and 0.06%).  The number of night-time, single-vehicle crashes resulting in death was reduced the greatest in places that introduced a 0.00% BAC restriction:








Potential issues

Without adequate enforcement, reducing the legal alcohol limit to zero may have reduced effect.  One Australian study has shown that young drivers are only less likely to drink and drive if random breath testing occurs.  Australia tends to utilise highly visible alcohol campaigns, including random roadside breath testing and “booze bus” enforcement in different locations at different times of day, as well as widespread advertising of alcohol-targeted enforcement campaigns.  This helps increase public perceptions that any driver can be and will be caught.  Encouragingly, the rate of youth drink driving has decreased considerably.

Another concern relates to the increase in blood alcohol limit from zero as a Provisional driver to 0.05% as a fully-licensed driver.  In Canada, new drivers typically complete their graduated driving licence program at the age of 18 or 19, at the same time when legal drinking commences.  This is the time when alcohol consumption and rates of binge drinking increase.  Research suggests increasing the legal drinking age, or extending the zero alcohol limit up until 21 years of age may be necessary to reduce the number of alcohol-related car crashes resulting in death. 

In Australia, the legal drinking age is also 18, but typically the Provisional driver does not progress to a full licence until between 20 to 22 years of age.  Nonetheless, the “coming of age” at age 21 is still a big celebration for many Australians, and Australian research has also demonstrated that the transition from a zero to 0.05% BAC limit is a difficult one.  Research has shown that estimating and counting “standard drinks” is difficult and young people often make inaccurate judgements when trying to calculate number of drinks by consumption time to determine if they have sobered up enough to drive.

Suitable alternative transport arrangements need to be in place for young drivers to help reduce drink driving – particularly in rural and remote areas where access to public transport is limited.  Australian research has found that convenience, the need to return home and lack of public transport are key reasons given for drink driving by young people.  One province in Canada has trialled a Community Drive Home Service, which allows a driver to call the service and request a lift home. In the United States a similar program has also been trialled successfully.

Factbase recommendations

A zero blood alcohol concentration limit for young and inexperienced drivers is effective – considerably moreso than a 0.02% limit – and therefore should apply to all Learner and Provisional drivers.  Adequate enforcement needs to be in place to deter young drivers from driving after drinking alcohol and efforts should be made to ensure adequate alternative transport arrangements are available in areas where alcohol is served.


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Blood alcohol concentration limits