Simon Bridges says the Government should be treating drug-driving with the same urgency it's dedicated to the Christchurch attack response.
Figures show more people die in crashes involving drivers with non-alcoholic drugs in their system than in crashes involving intoxicated drivers.
In 2017 there were 79 drug-influenced crashes, but only 70 over the legal alcohol limit.
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"I was a Crown prosecutor - I've seen so many victims and families, and I don't want to see anymore," the National Party leader told The AM Show on Monday.
He's "bloody angry" a Member's Bill introduced by National MP Alastair Scott which would have introduced roadside testing was voted down 63-56 last year.
"It's a saliva test, it takes about five minutes," said Bridges. "There's a slight inconvenience. But actually we can random drug-test the way we do the drink-driving booze buses."
Bridges said if the Government introduced its own saliva testing Bill, he would back it.
"Everyone agrees what happened in Christchurch was remarkably awful - 51 people died. Here though we've got over 70 a year. I'd like to see the same urgency on this."
Why National's Bill failed
During debate at the Bill's first reading, Labour MP Meka Whaitiri said the Attorney-General had found the Bill was inconsistent with the New Zealand Bill of Rights Act in several ways, including that it would require drivers to undergo a "compulsory random oral fluid test".
Green MP Chloe Swarbrick said the tests proposed under the Bill "are slow, expensive, and identify only three types of drugs, and only will detect their presence, not the impairment that they may be providing" and posed a risk of providing false positives.
Associate Transport Minister Julie Anne Genter told RNZ last year the expensive tests weren't necessary because we "already have an extremely effective impairment test which is over 90 percent effective usually backed up by 100 percent accurate blood tests". She also said National's proposed tests don't pick up many prescription drugs which impair driving ability.
National looked at introducing saliva testing in 2012, but decided against it after NZTA testing around half of users wouldn't be detected.
Prior to being in Government, Labour supported saliva testing - future Police Minister Stuart Nash calling himself a "huge supporter" as recently as 2016. Nash didn't speak during the debate on Scott's Bill.
Bridges promised if elected next year, saliva testing would be made law within National's first 100 days.
While more people died in crashes involving drugged drivers than drunk over the limit, there were more than twice as many deaths involving drivers under the influence of alcohol if you include people under the legal limit, figures show.