Key Takeaways:
- New Zealand is set to rollout roadside drug testing, starting with Wellington, with the rest of the country to follow by mid-2026.
- The tests will screen for four key drugs: THC, methamphetamine, MDMA, and cocaine.
- An Australian expert, Dr. Michael White, says the tests are nearly worthless in picking up impairment and are a scattergun approach.
- The government claims that 30% of all road deaths involve an impairing drug and that greater screening will improve road safety.
- There is a lack of robust evidence on whether roadside testing has reduced drug-impaired driving or accidents.
- The testing does not take into account the use of legal drugs, such as benzodiazepines and opioids, which can also result in fatal car accidents.
Introduction to Roadside Drug Testing
New Zealand is set to implement roadside drug testing, with Wellington being the first location to roll out the program next month. The rest of the country is expected to follow by mid-2026. The tests will screen for four key drugs: THC, which is found in cannabis, methamphetamine, MDMA or ecstasy, and cocaine. However, an Australian expert, Dr. Michael White, has expressed concerns that the tests are nearly worthless in picking up impairment and are a scattergun approach.
The Effectiveness of Roadside Drug Testing
Dr. White, an adjunct senior fellow at the School of Psychology at the University of Adelaide, has researched road accidents involving cannabis and says that the tests detected the drugs but do not reliably assess impairment. He points out that the problem is not just with the length of the detection window but how many people are actually impaired after taking drugs like cannabis. Regular cannabis users, for example, may not be impaired even if they test positive. Dr. White argues that this approach is a scattergun one, as many people who are regular users won’t be impaired even if they test positive.
Government Response
The government claims that 30% of all road deaths involve an impairing drug and that greater screening will improve road safety. Transport Minister Chris Bishop said earlier this year, "We know that they’re [drugs] a major factor in many road deaths and serious injuries. We’re now making sure that police are equipped with roadside oral fluid screening as a road safety tool to enable the enforcement." However, Dr. White points out that there has been no robust evidence as to whether roadside testing has reduced drug-impaired driving or accidents.
Differences Between Drugs and Alcohol
Dr. White also highlights the differences between how drugs and alcohol impair drivers. He says that policy should be based on crash risk, and that the crash risk from cannabis is relatively low, less than for a BAC of 0.5. In contrast, alcohol at a BAC of 0.5 doubles the risk of crashing. For methamphetamine, Dr. White says it is more difficult, as it might not actually impair a person but instead make someone more aggressive and increase their thrill-seeking behavior.
Concerns About Legal Drugs
Another key issue Dr. White has with the testing is with legal drugs such as benzodiazepines and opioids, which can also result in fatal car accidents. He cites Australian research that shows benzodiazepines account for twice as many road crash fatalities as cannabis, and opioids account for twice as many. Dr. White argues that neither Australia nor New Zealand takes into account the damage done by legal drugs.
Prescription Medications and Cross-Reactivity
Pharmacist and senior lecturer in Biosciences at AUT, Dr. Catherine Crofts, has also expressed concerns about the lack of information on what the new testing could mean for people with prescriptions like dexamphetamine. She notes that about 50% of people with ADHD in New Zealand are taking dexamphetamine or lisdexamfetamine, which is becoming increasingly popular. Dr. Crofts is worried about the potential for cross-reactivity with the tests, which could lead to false positives.
Alternative Methods for Assessing Impairment
Dr. White suggests that for subtle levels of impairment, some have suggested using phone applications to assess people’s reaction times. While he is not convinced that these apps are particularly good, he believes that at least they are trying to measure impairment, which is a step in the right direction rather than measuring presence.
Human Rights Concerns
Dr. White also notes that Australia and New Zealand do not efficiently take human rights into consideration when it comes to people getting taken off the roads without showing any good cause. In most other countries, drug testing is associated with some sort of test of impairment, and the police have to have some sort of good cause to take you off the road. The Attorney-General’s report into the legislation found it was inconsistent with parts of the Bill of Rights Act, specifically the right to be secure against unreasonable search and seizure, and the right not to be arbitrarily detained. Minister of Defence Judith Collins found the intrusion on privacy was not proportionate to the public interest objective.
