Drug driving law in New Zealand has changed significantly over the past year, and many drivers are unaware of how exposed they now are to prosecution.
If you have been stopped, tested, or charged in relation to drug driving, understanding the process and the law that applies to your situation is the first step in protecting your rights.
Roadside oral fluid testing
Since 15 December 2025, under the Land Transport (Drug Driving) Amendment Act 2025, Police have the power to stop any driver, anywhere, at any time, and require an oral fluid (saliva) test. Officers no longer need to suspect the driver of anything before requesting a test. The rollout began in the Wellington district and is expanding progressively, with nationwide coverage expected by around mid-2026.
The process works in two stages. First, a roadside screening test checks for four drugs: THC (cannabis), methamphetamine, MDMA, and cocaine. If that test is positive, a further saliva sample is taken and sent to a laboratory, where it is tested against a wider list of 25 qualifying drugs set out in Schedule 5 of the Land Transport Act 1998.
If the laboratory confirms the presence of one qualifying drug above the specified threshold, the driver receives an infringement notice with a $200 fine and 50 demerit points. If two or more qualifying drugs are detected, the fine rises to $400 with 75 demerit points. A positive result at both roadside stages also triggers an immediate 12-hour driving prohibition, regardless of whether the driver holds a valid prescription for the substance detected.
It is important to understand that these infringement-level thresholds are about the recent presence of a drug, not proof of impairment. A positive test does not necessarily mean a person was unsafe to drive, and there is ongoing debate, including from medical bodies, about how well oral fluid concentration correlates with actual impairment.
More serious driving offences involving drugs
Separate from the infringement regime, the Land Transport Act 1998 creates more serious criminal offences. Sections 57A, 57B, and 57C criminalise driving with one qualifying drug, two or more qualifying drugs, or a combination of alcohol and a qualifying drug, in the driver’s blood above specified concentration levels. Section 58 covers the broader and long-standing offence of driving, or attempting to drive, while under the influence of drink or a drug (or both) to the extent of being incapable of proper control of the vehicle.
A first or second conviction under section 58 carries a maximum penalty of three months’ imprisonment or a fine of up to $4,500, along with mandatory disqualification from driving for at least six months. For a third or subsequent conviction, the maximum penalty increases to two years’ imprisonment or a fine of up to $6,000, with mandatory disqualification for at least one year.
These charges can also arise alongside more serious matters, such as causing injury or death while driving under the influence, which carry substantially heavier penalties and are dealt with as indictable offences.
Defences and common issues
Not every positive test results in a conviction. Depending on the specific charge, defences may include: the drug being taken in accordance with a valid prescription, procedural failures in how the test was administered or the sample handled, issues with the chain of custody for laboratory samples, or challenges to whether the officer had lawful authority to require the test in the first place. Because the testing regime is new, and reliability of oral fluid devices has been the subject of ongoing scrutiny, there is real scope in some cases to challenge the evidential basis for a charge.
What to do if you are stopped or charged
If you are required to undergo a roadside drug test, you are generally required to comply, and refusing to do so is itself an offence carrying a 12-hour driving ban and further penalty. However, what happens after a positive result, including whether the charge can be defended or the circumstances mitigated, is where the real legal work begins.
If you have received an infringement notice, been charged under the Land Transport Act, or are unsure of your obligations following a roadside stop, getting advice early matters. Evidence, timing, and procedure can all affect the outcome of a drug driving matter.
Malcolm Dreaneen is a Henderson-based barrister with experience across criminal procedure, traffic prosecutions, and related civil and immigration consequences that can flow from a conviction. If you are facing a drug driving charge, contact MD Law for advice specific to your circumstances.
This article provides general information only and is not a substitute for legal advice about your particular circumstances.