Driving under the influence is a serious criminal offence in New South Wales. It occurs when a person operates a motor vehicle while their ability to do so is impaired by alcohol, an illicit drug, or prescription medication. A conviction can result in fines, imprisonment, and loss of your licence — making early legal advice critical to protecting your future.
What does DUI mean under NSW law?
Unlike a prescribed concentration of alcohol (PCA) offence, a DUI charge does not require a specific blood alcohol reading. Police can charge a driver with DUI based on observed impairment — for example, erratic driving, slurred speech, or the smell of alcohol or drugs — even if the driver returns a low or zero breath test result. DUI charges can also arise from impairment caused by cannabis, methamphetamines, prescription opioids, or any other substance that affects driving ability.
What does the prosecution need to prove?
To convict you of DUI, the prosecution must prove each of the following elements beyond a reasonable doubt. If they cannot establish any one of them, the charge cannot stand.
That you were driving — or in control of the vehicle
This sounds straightforward, but it is not always clear-cut. If police did not witness you driving — for example, they arrived after an accident or found you parked — proving you were the driver can be more difficult than it appears.
That it happened on a road or in a road-related area
The offence must have occurred on a public road or an area open to the public, such as a car park. It generally does not apply to private property.
That you were under the influence at the time of driving
This is the element that matters most, and it is where DUI differs from a standard drink driving charge. The prosecution cannot simply point to a breath test reading — they must show your ability to drive was actually impaired. To do this, they will typically rely on police observations of your behaviour, appearance and coordination, along with the results of any field sobriety or impairment tests conducted at the time. Things like slurred speech, unsteady balance, bloodshot eyes or the smell of alcohol will all form part of their case. So will anything you said to the police at the scene.
That the impairment was caused by alcohol or a drug
Where prescription medication is involved, this becomes more complex. It is not enough for the prosecution to show a substance was in your system — they need to establish it was affecting your capacity to drive at the time.
Why this matters for your defence
Because DUI is built on observed evidence rather than a number on a machine, there is more room to challenge the prosecution’s case. Police observations can be inaccurate. Field sobriety tests can be conducted incorrectly. Behaviour that looks like impairment can have an entirely innocent explanation — illness, fatigue, a medical condition, or anxiety at being pulled over.
These are the kinds of issues a criminal lawyer will examine carefully when advising you on your options.
Penalties for DUI in NSW
The penalty you face depends on whether this is your first or subsequent major traffic offence within five years. The court also has discretion to impose an interlock order, which may, where applicable, reduce the disqualification period.
| Driving under the Influence (DUI) | |
| First Major offence within 5 years | |
| Maximum Fine | $3,300 |
| Maximum Imprisonment | 18 Months |
| Automatic Disqualification Period | 3 Years |
| Minimum Disqualification Period | 18 Months |
| Second Major offence within 5 years | |
| Maximum Fine | $5,500 |
| Maximum Imprisonment | 24 Months |
| Automatic Disqualification Period | 5 Years |
| Minimum Disqualification Period | 2 Years |
Interlock orders and licence disqualification
In some cases, the court may make an alcohol interlock order as an alternative to a full disqualification. An interlock device is fitted to your vehicle and requires you to provide a breath sample before the engine will start. Where the court makes an interlock order, the mandatory disqualification period may be reduced. Whether an interlock order is appropriate depends on the circumstances of your matter and your prior driving history.
Possible defences to a DUI charge
Being charged with DUI does not automatically mean you will be convicted. Several defences may be available depending on the facts of your case:
- Unlawful testing procedure — If the breath, blood, or sobriety test was not conducted in accordance with the law, the evidence obtained may be inadmissible.
- You were not the driver — The prosecution must prove beyond a reasonable doubt that you were the person driving or in control of the vehicle at the relevant time.
- Not impaired at the time of driving — The prosecution must establish that you were actually under the influence at the time of driving. In some cases, evidence of impairment may be challenged or explained by other factors.
- Honest and reasonable mistake — In limited circumstances involving prescription drugs, a genuine lack of knowledge about a medication’s impairing effects may be raised as a defence.