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Blood alcohol content limits

Blood alcohol content limits

What is blood alcohol content or BAC?

Blood alcohol content or BAC is the measurement of the number of grams of alcohol in 100ml of blood. If you are the driver of a vehicle in a public place, the police may take a sample of your breath, blood or urine and apply tests to determine your BAC.

Offences of drink driving under the Road Traffic Act 1974 (WA) are described according to the BAC level, for example excess 0.08 BAC. The penalty for the offence (usually a fine and loss of licence) increases as the BAC reading increases and the penalty may also increase if it is your second or subsequent offence.

Is there a legal BAC limit?

Depending on the type of licence you hold and the current status of your licence, you will have a particular legal limit on the amount of alcohol you are allowed to have in your system when you are driving.

The following information sets out the various limits and when they will apply.

Who is subject to a 0.00 BAC limit?

The 0.00 BAC limit, meaning that you are not allowed to drive when you have any alcohol in your system, applies where:

  • you are a novice driver
  • your driver’s licence is currently disqualified for an offence of driving under the influence (DUI)
  • your driver’s licence is currently disqualified for failing to comply with a request to take part in a breath, blood or urine test (failing to comply)
  • your driver’s licence is currently disqualified for a second or subsequent 0.08 BAC offence
  • your driver's licence has been cancelled as a result of a conviction for DUI, driving impaired by drugs, failing to comply or refusing a driver assessment or sample request and have been previously convicted of DUI, excess 0.08, driving impaired by drugs, failing to comply or refusing a driver assessment or sample request
  • your driver's licence has been cancelled as a result of a conviction for excess 0.08 where you have been previously convicted for DUI, excess 0.08, driving impaired by drugs, failing to comply or refusing a driver assessment or sample request in the five years preceding the conviction for excess 0.08 
  • you hold an extraordinary driver's licence, and
  • you are a recently disqualified driver.

You will also be subject to a 0.00 BAC limit if you drive a motor vehicle that:

  • can carry more than 12 adults (including the driver) and at the time you are carrying passengers
  • is an omnibus and you are carrying passengers for hire or reward
  • is a taxi (with taxi plates or a taxi licence) and at that time you are carrying passengers for hire or reward
  • has a gross combined mass exceeding 22.5 tonnes, or
  • is a specific vehicle carrying dangerous goods.

If you are on P-plates and you are also a novice driver, you are subject to a 0.00 BAC limit. However, if you are on p-plates but you are not a novice driver, you are subject to a 0.05 BAC limit. 

What is a novice driver?

You are a novice driver if you have held a licence for a period of less than two years or a period adding up to less than two years. In calculating how long you have held a licence, the period can include any period when you have held an interstate or overseas driver's licence, but cannot include:

  • any period when you were excluded from driving by law, or
  • any period when you were driving under a learner's permit (on L-plates).

What is a recently disqualified driver?

You are a recently disqualified driver if within the last three years:

  • you ceased to be subject to an order disqualifying you from holding or obtaining a driver’s licence for DUI, failing to comply with a request for a test or for a second or subsequent excess 0.08 BAC offence, or
  • you have been re-issued a driver’s licence that had previously been cancelled for prior drink driving offences.

Who is subject to a 0.02 BAC limit?

If you are subject to a 0.00 BAC limit you will also be subject to a 0.02 BAC limit (both limits apply to the same people). If you are subject to a 0.00 BAC limit and you provide a BAC reading between 0.02 and 0.05 you may be charged with an offence of excess 0.02 BAC rather than an offence of excess 0.00 BAC. A charge of excess 0.02 BAC is more serious and attracts a mandatory licence disqualification, while a conviction for an offence of excess 0.00 does not.

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 more than a 0.05 BAC reading.

What happens if I drive when I am over the limit?

If you are found to be driving with more than the allowable amount of alcohol in your system, you are committing an offence of drink driving under the Road Traffic Act 1974 (WA).

The offence you are charged with will depend on the actual amount of alcohol found to be in your system at the time of driving, that is the BAC reading. The penalty, which is a fine and loss of your license, increases as the BAC reading increases and the penalties may also increase if it is your second or subsequent offence.

If you dispute the amount of alcohol said to be in your system at the time of driving, or you think you have been charged with a drink driving offence that is based on the wrong BAC limit, you should seek legal advice.

You can seek legal advice before court from your own private lawyer or a Legal Aid WA duty lawyer may be able to assist you on the morning of court. Click here for more information about Legal Aid WA's Duty Lawyer Service.

Where can I get more information?

See the following related Legal Aid WA web pages:

Last reviewed: 02/09/2015

Last modified: 8/06/2016 5:12 PM

Disclaimer

The information displayed on this page is provided for information purposes only and does not constitute legal advice. If you have a legal problem, you should see a lawyer. Legal Aid Western Australia aims to provide information that is accurate, however does not accept responsibility for any errors or omissions in the information provided on this page or incorporated into it by reference.