What Is A DUI?

DUI is shorthand for driving under the influence. It usually refers to driving while your ability is affected by:

• Alcohol
• Illicit drugs
• Prescription medication
• Over-the-counter medication that impairs alertness
• A combination of substances

A DUI-style allegation does not always require a crash. Police can charge a person based on testing results or observed impairment even if nobody was hurt and no property was damaged. Courts treat DUI-style conduct seriously because impaired driving increases crash risk, increases severity of harm, and puts other road users at risk.

The exact legal definition depends on the jurisdiction. Some offences are based on a numerical threshold ( an alcohol concentration above legal limit). Other offences focus on impairment, which means the prosecution must prove you were actually affected to a level that made you unsafe to drive.

What Is The Legal Definition Of A DUI?

DUI is common shorthand, but legally it only means what a statute says it means. In many jurisdictions, DUI is an impairment-based offence. The prosecution must prove alcohol, drugs, or both affected the person’s driving ability to a defined legal threshold. This is different from “over-the-limit” offences, which rely on a reading such as blood alcohol concentration (BAC) or breath analysis result.

DUI is about impairment, not just numbers. You can be under the general BAC limit and still be charged if impairment is proved. You can also be over the prescribed BAC limit and be charged even if you appear “fine”. Many DUI-style offences are treated as conduct offences, meaning the prosecution does not need to prove a crash, injury or damage.

In New South Wales, What Is Considered DUI Under The Law?

In NSW, the offence commonly referred to as “DUI” is in the Road Transport Act 2013 (NSW) section 112. In substance, it prohibits using or attempting to use a vehicle while under the influence of alcohol or any other drug, where the person is incapable of having proper control of the vehicle. The prosecution must prove impairment to that legal threshold, not merely that a substance was consumed.

“Driving” is not always required. Section 112 covers driving, but it also covers occupying the driving seat and attempting to put the vehicle in motion. It can also apply to a fully licensed driver supervising a learner driver from the passenger seat in certain circumstances.

NSW road safety guidance also makes clear that police can stop drivers and conduct random breath tests, including after a crash, and refusing a breath or blood test can be a separate offence with serious consequences. For drug-related impairment, police can use roadside saliva testing for certain illicit drugs, and they may conduct a sobriety assessment if they suspect drug impairment. Failing that assessment can lead to arrest and hospital-based blood and urine sampling.

Evidence is usually built from a combination of roadside observations, driving manner, footage (body-worn video, dashcam, CCTV), witness accounts, timelines, and any admissions or medical material that supports or challenges impairment. For this reason, the case often turns on the reliability and completeness of what was recorded, not one single test result.

Promptly request police disclosure, including body-worn video and station records, because early preservation can prevent avoidable evidence gaps.

Why Is Driving Under The Influence Illegal?

DUI laws exist because impaired driving increases crash risk and the severity of harm when crashes occur. Alcohol and many drugs can slow reaction time, reduce attention, distort judgment, and increase risk-taking. Even mild impairment can matter in real traffic conditions.

The law also reflects the duty of care drivers owe to other road users. DUI offences aim to prevent predictable harm by deterring unsafe driving choices and enabling enforcement before a serious crash occurs.

If you are facing a DUI charge, we can represent you in court, test the prosecution case, advise on defences and negotiation options, and prepare a strategy for the best available outcome.

Difference Between DUI And DWI Charges

“DWI” (driving while intoxicated or impaired) is used mainly in the United States, and its meaning depends on the state. In some places, DUI is broader and DWI is used for higher BAC levels. In others, the terms overlap or one term is not used at all.

For Australian readers, the key is not the label but the precise offence wording and what must be proved under the relevant state or territory legislation.

What Is A DUI Called In Australia And NSW?

Australia does not use a single national “DUI” label. People commonly say “drink driving” or “drug driving,” while legislation refers to PCA offences (prescribed concentration of alcohol), “driving under the influence,” “driving with a prescribed illicit drug present,” or combined alcohol and drug offences.

In NSW practice, people often say “DUI” to describe the section 112 offence, but charge sheets and court documents may use the legislative wording. The label matters because it affects what must be proved and what evidence is most important.

Common NSW impaired-driving labels and what they usually mean

Is A DUI A Criminal Conviction In Australia?

In Australia, DUI-style offences are prosecuted in criminal courts (most commonly the Local Court or Magistrates Court). They are not just “administrative” rule breaches. Courts can impose penalties including disqualification, fines, and imprisonment in serious cases.

People sometimes describe these as “traffic offences,” but if a court records a conviction, it is still a conviction and can carry long-term consequences.

Does A DUI Go On Your Criminal Record In Australia?

A DUI can appear on your criminal record if it results in a conviction. A charge is not the same thing as a conviction. If the matter is dismissed or finalised without a conviction being recorded (where a non-conviction outcome is legally available), the long-term record impact can be very different.
Even where a conviction is recorded, spent convictions schemes can limit disclosure after a crime-free period, subject to exceptions. The detail differs across jurisdictions and can depend on the type of check requested.

Does A DUI Show Up On A Police Check?

Police checks are commonly used for employment, licensing, visas, and volunteer screening. Whether a DUI shows up depends on the type of check, whether there was a conviction, and whether any spent convictions scheme applies. Some regulated roles treat driving offences as directly relevant.

As a practical risk assessment, if you are convicted of a DUI-style offence, assume it may be disclosed on a police check for at least some period.

It is also important to distinguish convictions from pending matters. Some standard checks focus on final outcomes, while other screening processes (especially licensing or regulated roles) may require you to disclose current charges, court dates, or licence sanctions even before your case is finalised.

Difference Between DUI And PCA Offences

In NSW, DUI and PCA offences are separate because they target different risks and require different proof. PCA offences are measurement-based. DUI is impairment-based.

PCA is about whether your BAC or breath reading falls within a prescribed range, regardless of whether you look impaired. DUI is about whether alcohol or drugs affected you to the level that you were incapable of having proper control, even if there is no BAC figure relied on. A person can also face both types of allegations from the same incident, depending on evidence and charging choices.

DUI vs PCA in NSW

PCA ranges are typically described by bands (for example, low, mid, and high range), and some drivers are subject to a zero limit. DUI does not depend on which band applies. It depends on whether the evidence shows loss of proper control due to alcohol or drugs.

What Substances Can Lead To A DUI Charge?

DUI is not limited to alcohol. In NSW it can be based on alcohol, illicit drugs, prescription medications, or combinations. Substances linked to impairment-based allegations commonly include alcohol, cannabis, stimulants (such as cocaine or methamphetamine), sedatives and sleeping pills, and opioid pain medicines, particularly where they affect alertness, coordination, or reaction time.

NSW also has presence-based drug driving offences for certain illicit drugs, where detection can be enough even without proven impairment. That is why it is important to identify exactly what offence is alleged.

What Is The Blood Alcohol Concentration Limit In DUI Cases?

BAC measures the concentration of alcohol in blood and is often estimated through breath analysis. In NSW, legal BAC limits depend on licence type and vehicle type. NSW Government guidance sets a zero BAC requirement for learner and provisional drivers, a general limit of under 0.05 for most unrestricted licence holders, and a lower limit of under 0.02 for certain higher-risk categories.

The under 0.02 category commonly applies to drivers of public passenger vehicles (such as buses, taxis, rideshare and hire cars), heavy vehicles over 13.9 tonnes, vehicle and trailer combinations over 13.9 tonnes, and dangerous goods vehicles.

NSW BAC limit snapshot (check your licence category)

BAC is not required to prove a DUI offence in NSW. DUI focuses on impairment and control, not a specific BAC range.

What Does Incapable Of Having Proper Control Mean In DUI Law?

“Incapable of having proper control” describes impairment that materially affects safe driving ability. Courts look at the whole picture, not a single sign. Evidence may include erratic driving, poor lane control, delayed braking, unsteadiness, slurred speech, disorientation, or inability to follow instructions.

Defence issues can include whether the signs have another explanation such as fatigue, injury, medical conditions, language barriers, or shock after an incident, and whether the available records capture the full context.