A drug testing expert has raised concerns about the accuracy of the equipment needed to conduct roadside drug testing, as the Government considers a law giving police new powers to crack down on impaired drivers.
Drugged drivers are an issue on New Zealand roads, with Associate Transport Minister Julie Anne Genter saying 103 people died last year in crashes where the driver was later found to have drugs in their system.
The Government is now looking to introduce random roadside testing for a number of substances using saliva tests, with the Land Transport (Drug Driving) Amendment Bill currently at Select Committee stage.
Attorney-General David Parker has said the bill, as it stands, seems to be at odds with New Zealand's Bill of Rights due to a lack of definition in the bill around how much of a substance must be present for a person to be infringed to be prosecuted.
The current suggested regime would have police testing for a positive or negative result for drugs, rather than measuring for a certain concentration, and there are currently no grounds for judging how impaired a driver is by those concentrations.
Genter has said those grounds are coming and will be added to the bill once an expert panel, delayed by Covid-19, has had time to formulate the limits.
However, the head of a Kiwi drug testing agency says the technology needed to accurately test drivers in line with those limits is still "a couple of years away".
TDDA CEO Kirk Hardy, a former police drug squad detective, said saliva testing devices used overseas to conduct the tests had some history of providing false negatives, which could see impaired drivers sent on their way.
"It's certainly not there at the moment in terms of accuracy, and particularly around stuff like THC and prescription medications like benzodiazepines - there's been some real issues and that's come about recently with some case law as well, in the workplace side of things, in terms of failing to detect people using cannabis recently, while they're intoxicated, and then while they're impaired as well, which is after the acute intoxication stage," Hardy said.
"There is a demand for a cannabis breathaliser around the world, but the technology's just not there and I can't personally see it being there for maybe at least 12 to 24 months - then they're going to have to go through trials.
"And then what do you do with the other drugs? You've got a cannabis breathalyser, what do you do for meth, what do you do for cocaine, what do you do for synthetic cannabis, prescription medications - the list goes on.
"If we're going to go along with what the government is wanting at the moment, which is a massive array of drugs to be tested for, I applaud them for that, but I think we're just a little bit over-ambitious in thinking that's going to work and that we're going to get that done quickly, because it just isn't going to happen unless we sacrifice a lot of accuracy, which I don't think we should be doing.
"So there are some real big issues and hurdles we need to get over."
Mr Hardy also said the results of saliva tests could be influenced by a driver eating or drinking after using drugs, and that breath testing for drugs was a more accurate measure - but the technology to do so accurately is still being developed.
"They are talking about hand-held breath testing devices being developed around the world, but even those are a long way away," he said.
"I think with some of the manufacturers of these devices, what they say the device does, what it actually does and the field, are certainly two different things - in the lab, they'll perform extremely well - they can say, hey, look, this device gets 90-something per cent.
"However, when you put it in a environment with vibration, humidity, you've got people interpreting results differently, or collecting the sample differently."
Hardy said he understood the need to take action against drugged drivers, and that a bill to develop the laws supporting that needs to be "pliable" to some degree, but described the current bill as being "a little bit over ambitious.
"I don't think the technology is 100 per cent pure at the moment, but I also think that some testing is better than none," Hardy said.
"Maybe a few of the experts at the front end saying, hey, these are the challenges we need to be thinking about beforehand, before putting it in front of a select committee, probably would have helped, because we wouldn't be in this position we're in now.
"But at same time, we're discussing it and I guess that's the benefit as well, that it's brought it out into the open - what are the solutions around this? How do we tackle this now?"
Hardy said he recognised the need for a deterrent to drug driving, and that "if you can deter one person from getting behind the wheel while they're stoned or under the influence of another drug then you've probably achieved what you wanted to - because what price do you put on a life?
"It's just devastating for someone to lose someone in a fatality caused by something that could have been prevented.
"Yes, you'll have court cases - that's something you'll have to accept - but I think if you can get something up and running and at least deter a few people and save some lives in the process, then that's got to be a good thing, surely."
He said New Zealand could consider taking the same approach as South Australia, which conducts random roadside tongue swabs for three substances - cannabis, MDMA and amphetamines - and then sends a second sample away to be analysed in a laboratory.
"They've probably adopted the best of both worlds when you look at it, because they do the tongue scrape for the three drugs - and then if they get an indication they simply forbid them to drive for 48 hours, and they take a further sample and it goes off to the lab.
"At the moment, with the technology available, I think that's probably the best."
He said the Government should consider reducing the number of substances being tested for in order to reduce the time drivers would be stopped for, and that police should be given additional training on recognising the signs of an impaired driver.
"I think that's probably the important thing - if you put a lot into that training so those front lines cops who are pulling people over, they put them on the breathalyser and they blow zero, and they go, you know what, something's not quite right here - it's not alcohol, but it's something."
The Land Transport (Drug Driving) Amendment Bill is currently open for public consultation.