Blood alcohol content limits
You will usually lose your licence if you drive a motor vehicle with a blood alcohol content (BAC) higher than you are allowed. Your exact charge will depend on the BAC in your system. Different drivers have different legal limits.
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This information will help you understand:
- What blood alcohol content (BAC) means
- What the BAC limits are
- Who is subject to a 0.00 BAC limit
- Who is subject to a 0.05 BAC limit
- The penalties for driving above your BAC limit
What is blood alcohol content?
Blood alcohol content (BAC) is the measurement of the number of grams of alcohol in 100ml of blood. Drink driving offences are described according to your BAC level. For example, excess 0.05, excess 0.08, and driving under the influence (above 0.15).
What are the BAC limits?
Your BAC limit depends on the type of licence you have and the status of your licence. Most people are subject to a 0.05 alcohol limit, although some people are subject to a 0.00 alcohol limit.
Who is subject to a 0.00 BAC limit?
A 0.00 BAC limit means you cannot have any alcohol at all in your blood when you drive. There are many examples of people subject to a 0.00 alcohol limit. You might not be aware of them all.
Some examples are:
- Novice drivers
- Alcohol offenders and Interlock restricted driver licence holders
- Heavy vehicle drivers
- Drivers of vehicles carrying dangerous goods
- Taxi drivers, who are carrying passengers for hire or reward.
For more information about who is subject to a 0.00 alcohol limit is available from the Department of Transport.
If you are subject to the 0.00 BAC limit, it is an offence to drive with any amount of alcohol in your body. If you have consumed alcohol and drive with a BAC at 0.02 or above, you could be charged with a more serious offence (excess 0.02) and your licence must be disqualified from driving for a period of time.
Who is subject to a 0.05 BAC limit?
Every driver who is not subject to a 0.00 BAC limit, is subject to a 0.05 BAC limit. Therefore, it is always an offence to drive with a BAC reading at or above 0.05.
What are the penalties for driving over my BAC limit?
There are a range of penalties that the court might impose for a drink or drug driving offence. The most common penalty is a fine and disqualification of your licence for a certain period. Your licence might also be cancelled. For some serious drink driving offences you can also go to prison.
If you are charged with an excess 0.08 or DUI (excess 0.15) offence, you will normally be given an immediate licence disqualification notice from the police (often called a roadside disqualification). This lasts for 2 months, and any other disqualification imposed by a court for the offence can take into account how long your licence has already been disqualified under the roadside notice.
For some offences you might also be subject to the Alcohol Interlock Scheme. You will then need to meet certain requirements from the Department of Transport before being permitted to drive.
There is more information about BAC limits and a range of drink driving related offences, including alcohol interlock offences, in the Legal Aid WA Infosheet - Traffic - Part 2: Common offences and penalties.
Resources from Legal Aid WA
More information
Department of Transport
- Driving offences (speeding, alcohol and traffic)
- Immediate licence disqualification
- Alcohol Interlock Scheme
Road Safety Commission
Last reviewed: 30 May 2024