Blog - Calls for change in roadside drug testing

Police officer talking to driver

A recent article has highlighted concerns about the roadside drug testing program conducted in NSW. It suggests that the detection process is flawed as it may capture individuals who had previously used recreational drugs (such as cannabis) but who were not impaired by drugs at the time of testing. There are several important issues raised in the story, along with some misconceptions.

The first is that impairment is the basis of prosecution under road traffic legislation. Workplace and roadside alcohol (and drug) testing in Australia is a per se test. That is, workers and motorists are required to have alcohol and drug concentrations below prescribed levels in order to not breach the legislation. It is irrelevant whether they are impaired or not. In contrast, the US legislation often relies upon demonstration of impairment in intoxicated motorists. This includes making motorists suspected of drink driving perform acts and tests to assess their level of impairment, including reciting the alphabet backwards, walking on a straight line, balancing on one foot, and so on.

The main reason for this difference in approach is that the Australian method removes any defence in which a person who has consumed significant drug or alcohol may not be readily identified as impaired, lacking the external visual cues that suggest intoxication. In the absence of these cues a persons judgement and attention to skilled tasks such as driving may still be considerably affected.

The second matter in the story is the nature of testing, and the conclusions that may be drawn following testing. As clearly stated in the article, urine testing detects primarily metabolites of THC, the active component in cannabis. These may be pharmacologically inactive so detection does not necessarily suggest impairment. However, oral fluid (saliva) testing measures only THC, the active agent. The level of oral fluid THC is a more direct marker of impairment. Hence roadside oral fluid tests are unlikely to incorrectly identify ‘sober’ drivers as ‘impaired.

It seems that reading between the lines, the issue is one of the advice offered by Government regarding the testing regime. Where advertising material advises motorists that THC may persist in detectable quantities for “… 8 hours, or even longer…” a cannabis consumer may believe they are ‘safe’ to drive after 8 hours. However, heavier use, and individual predisposition, may mean that THC is detectable for longer in roadside tests, perhaps exceeding 24 hours. Those motorists detected after they claim to have not consumed THC for a long period may feel unfairly treated as a result of this advice. This is akin to a drink-driver claiming that their 0.010% alcohol result the day after a booze binge is unfair and is clearly perverse.

My impression of the article is that it is more a vehicle for the legal profession to advertise potential legal challenges to drug driving convictions and may be an opportunity to obtain more clients. Call me cynical, but the article itself answers the question. Does roadside testing work? Absolutely.

Boilerplate John

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