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Roadside Cannabis Drug Tests Often Return Wrong Result, Aussie Study Finds

Roadside Cannabis Drug Tests Often Return Wrong Result, Aussie Study Finds

"Imagine using a breathalyser that 16 per cent of the time didn't detect that a driver was intoxicated."

Stewart Perrie

Stewart Perrie

There has been a lot of contention about roadside drug tests in Australia ever since the technology was able to be rolled out en masse.

Police have since been drug testing people alongside Random Breath Test operations and nabbing loads of people who are high.

However, a new study from the University of Sydney has revealed that when it comes to cannabis, the tests often get the wrong result.

Two of the most common devices used by police, the Securetec DrugWipe, and the Draeger DrugTest 5000, were used in this study, which has been published in the journal Drug Testing and Analysis.


Thomas Arkell, a PhD student at the University of Sydney, wrote: "What we found was that these test results often came back positive when they should have been negative, or conversely that they came back negative when they should have actually been positive.

Strangely, when there were high traces of THC, the psychoactive ingredient in weed that gets you high, there was a nine to 16 per cent chance of the test coming back negative.

On the flip side, when there were very low or negligible traces it came back with a false positive five to 10 per cent of the time.

Sydney University's Lambert Initiative for Cannabinoid Therapeutics academic director Iain McGregor. said: "Imagine using a breathalyser that 16 per cent of the time didn't detect that a driver was intoxicated, and 5 per cent of the time pinged them if they were only at .01 or .02.

NSW Transport

"Detecting impairment due to cannabis use is an important goal in promoting road safety, but using saliva tests to do this appears fraught with issues."

Different drugs stay in your system for different lengths of time, according to Drug Abuse. Cocaine can be detectable up to two days after your bender, 72 hours for MDMA and at least seven days when it comes to weed.

It's worth noting that if you do test positive for drugs during a roadside test, you're asked to submit to a second one with more sophisticated equipment.

But there has still been a growing chorus of people against the standard drug testing of motorists over fears that they're just not accurate enough.

Australian Lawyers Alliance is calling for an overhaul of state's and territory's drug testing laws, with spokesperson Greg Barns telling 3AW: "You could have a person who has had some drugs on a weekend and is then driving on the Monday.

"There's nothing wrong with their driving at all, they just get caught on a roadside test and they lose their license for a long time.

"The legislation was designed to stop impairment in driving, in other words to stop people who might be unsafe on the roads. That's the way drink driving laws work, but they don't work that way with drug driving."

But don't expect changes any time soon.

Featured Image Credit: NSW Transport

Topics: Interesting, Drugs, Community, Australia