Drivers could be stopped at random and tested for drug-driving if a new Member's Bill is passed into law.
National MP Alastair Scott wants drivers randomly tested for cannabis, MDMA and methamphetamine - and the Government is open to the idea if the testing technology is good enough.
"The current law doesn't do enough to deter drug-impaired people from getting behind the wheel - Police must have good cause to suspect that a driver is impaired by drugs before requiring them to stop and take a behavioural test, like walking heel to toe in a straight line," he said on Tuesday.
"Police roadside testing is a much stronger and more visible drug driving enforcement measure which will help deter people from driving while under the influence of drugs.
"It will also improve police's ability to catch those who do before they cause a crash."
Minister for Police Stuart Nash is leaving the door open for discussions.
"I am open to hearing Alastair Scott's ideas for a law change, if that is required. If technology exists to allow for this type of roadside testing in a timely, efficient and reliable way, we should be looking at it," he said.
That squares with comment made by Mr Nash last year, when he was Labour's spokesperson for police. "As soon as we get the technology in place I think it has got to be rushed out, because people who are high behind the wheel, I think, are just as much a danger as those who are drunk," he told NZME in July.
But the question of accuracy could make the Bill hard to stomach for the Government.
The New Zealand Drug Foundation told RNZ in August the tests will miss most drugs because they don't test for prescription drugs. Executive Director Ross Bell said the tests frequently produce false positives and false negatives.