The Government has been urged to introduce random roadside drug testing immediately. But New Zealand researchers who are working on an innovative drug test say the equivalent of a booze bus for drugs is a long way off.
New Zealand scientists are developing a test which could quickly detect whether a motorist has been using methamphetamine.
It is hoped that the testing method being devised by the Institute of Environmental Science and Research (ESR) and a New Zealand biotech company could eventually be used for roadside testing and cover other drugs including cannabis and synthetic cannabis.
But as advocates and politicians agitate for the urgent introduction of a testing regime, researchers warn that a fast, effective drug-testing device is possibly years away.
The Government is seeking public feedback on ways to improve roadside drug-testing. It comes after pressure from the National Party to take action on the issue and pleas from families of victims killed in drug-related crashes.
Under the existing rules, police can only drug-test drivers they suspect of consuming illicit or legal drugs. The only test available here is impairment testing such as walking in a straight line or standing on one leg. A blood test can then be sought.
ESR forensic toxicologist Dr Helen Poulsen, who specialises in the area, said other countries had introduced roadside saliva tests but there were a range of problems with this approach.
The tests show the presence of drugs in a driver's system. But they do not show how impaired a driver is. And there is no direct link between a driver's level of consumption and how it affects their driving.
Overseas jurisdictions have set limits on how much drugs can be in a motorist's system - or in some cases have introduced a zero tolerance approach for certain drugs.
"But those limits are set more for ease of prosecution rather than saying this person is impaired at that level," Poulsen said, "Because they could never say that."
In Canada, where drug-testing of drivers is most advanced, police have found that their testing device is unreliable and that it produced false positives - meaning people were found to have drugs in their system when they had not consumed anything.
ESR and New Zealand-based company AuramerBio hopes to overcome some of these obstacles with new technology which would quickly detect targeted drugs using a driver's saliva.
The technology uses synthetic DNA that is programmed to recognise specific drugs which could impair driving. The DNA is wrapped around gold nanoparticles and when they are in the presence of a targeted drug the nanoparticles are released and clump together, giving a colourful reaction.
The first step for the researchers is getting the DNA strand to detect meth and not other drugs. Then it must detect the right amount of the drug, so it is not picking up traces of meth on people who have not used the drug. And lastly it must be put into a device which can be used by police at checkpoints and produce consistent results.
"So we're a wee way off having anything at the roadside," Poulsen said.
There is a further obstacle. For it to get public buy-in, any test must be relatively efficient.
"The inconvenience factor isn't a small thing," said NZ Drug Foundation head Ross Bell.
"If we started stopping people at random roadside alcohol checks with people having to wait ten minutes, we run the risk that people stop respecting police," he said.
In Australia, roadside saliva tests for cannabis, meth, and MDMA can take 10 or 15 minutes to produce a result. For that reason, police only pull over five cars at a time rather than resting every car.
On Wednesday Police Minister and Associate Transport Minister Julie Anne Genter revealed plans to improve drug driver testing were to be opened for public consultation.
The announcement had previously been delivered to Parliament calling for an urgent law change on roadside testing.
Last week the Government was also urged to give police more support on drug-testing of motorists.
The call was made by Logan Porteous who lost his parents Ian, 80, and Rosalie, 76, in a crash which claimed seven lives in Waverley last year. Rosalie's sister Ora Keene, 84, and her friend Brenda Williams, 79, also died; as did the driver of the other car who had been smoking synthetic drugs prior to the crash, Jeremy Thompson, 28, his newborn daughter Shady, and 8-year-old step-daughter Nivek Madams.
After the Coroner's inquest into the crash, Logan said: "We will, as a family, fight for this in the name of the innocent people who were killed in this accident, as a result of a driver under the influence of drugs."
Porteous noted how quickly the Government had changed gun laws after the Christchurch mosque shootings.
"So it can be done again, it's up to the politicians."
Porteous said he was numb after hearing the evidence that the crash was caused by drug-driving.
"To be honest, right now the grief hasn't hit me, it's just something you have to deal with," he said.
"Everyone has a choice to either drink, or in this situation take drugs, then get in a car."