Driving with Alcohol or Drugs in Your System 

In Queensland, anybody who holds a driver’s licence would know that it is illegal for a person to drive a motor vehicle if there is a certain level of alcohol in their system. However, this area of law is not as straightforward as it might seem. At our law firm in Brisbane (and our other locations) we constantly receive queries about what a driver’s rights and obligations are if they are facing a situation that involves the driving of a motor vehicle while they have alcohol or drugs in their system.

How is alcohol measured in a person and what can affect this reading?

There are a number of ways that the amount of alcohol in a person’s system can be measured. The most popular ways are through the taking of a sample or breath or a sample of blood. In Queensland, the traditional method is through a sample of breath because it is quick, cheap and usually very accurate.

The taking of a sample by blood is only done in rare cases, such as the person is not able to provide a sample by breath (because they might be seriously injured or unconscious). There are a number of protective measures in place to ensure that a person’s blood is not taken without a good reason.  The first sample is usually taken by the roadside with a handheld device.  If it is a positive reading, then the person will be transported back to the police station or a mobile van that has the proper testing equipment.

Blood or breath alcohol concentration (BAC) is the amount of alcohol in your body and is measured by the concentration of alcohol in your breath or blood. It is measured in grams of alcohol per 100 millilitres of blood. For example, a BAC of 0.05 means your body contains 50 milligrams of alcohol per 100 millilitres of blood. As soon as a person starts drinking, their BAC rises and it takes 30 to 60 minutes after they have stopped drinking for the BAC to reach its peak.

Factors that can affect your BAC include:

  • how much alcohol you drink
  • the time period over which you consume alcohol
  • how much you weigh
  • how long since you last ate
  • whether you are fit
  • how healthy your liver is
  • whether you regularly drink
  • your mood
  • your gender
  • the type of drink(s) you consume.

How much alcohol can I legally have in my system?

Queensland has four alcohol limits. These limits are used to apply penalties if a person is caught driving with an illegal blood or breath alcohol concentration (BAC) for their licence.

The limits are:

  1.     ‘no alcohol’ limit – BAC must be no greater than zero. This applies to people who are on a learner or provisional licence, as well as some people on their open licence if they are driving certain vehicles or for certain reasons.
  2.     general alcohol limit – BAC is between 0.05 and 0.999.
  3.     middle alcohol limit – BAC is between 0.10 and 0.149.
  4.     high alcohol limit – BAC is equal to or greater than 0.150.

What if I refuse to provide a sample?

If a person refuses to provide a sample to the police then they will be charged as though they had a high alcohol limit (that is, greater than 0.150). This is to stop a person who knows that they have an illegal reading refusing to provide a sample in the hope that they won’t be charged with drink driving offences

Is it illegal to drive with drugs in my system?

A lot of people still don’t know that it is illegal to drive with drugs in their system ie. they have committed drug offences. Rather than being taken by breath, the test for drugs is done by a saliva sample and unlike alcohol, it is not possible to determine how much drugs are actually in a person’s system. The offence/s, therefore, is simply that the person drove with some drugs in their system, meaning that the person may have consumed the drug days earlier and can no longer even feel the effects of the drug.

Not all drugs are able to be detected – only cannabis, MDMA (ecstasy) and methylamphetamine (ice or speed) can be detected. Other states, such as New South Wales, are in the process of implementing roadside testing for cocaine but this is not yet the case here in Queensland.

What are the consequences of being charged with driving with an illegal alcohol reading or drugs present in saliva?

These criminal offences must always carry a period of licence disqualification together with a penalty which can include a term of imprisonment. It depends on a number of things, such as the circumstances of the offence, the alcohol reading and the person’s personal circumstances, traffic and criminal history.

In some circumstances it is possible to apply to a ‘restricted licence’, allowing a person to continue driving. However, there are many conditions that need to be satisfied and it is therefore always recommended that a person speaks to a lawyer before they take any action.

If you’re needing assistance with legal matters or understanding your legal rights (including drink driving offences) Cridland & Hua are the specialists amongst Brisbane Law Firms, practising exclusively in criminal and quasi-criminal law. Contact us today. 

Back to all articles