The Government has revealed more details about new road safety measures.
From December, police in Wellington will do random roadside saliva tests - screening for cannabis, methamphetamine, MDMA, and cocaine.
Drivers coming back positive will need to do a second test that checks for 25 substances.
Transport Minister Chris Bishop says the swab could detect drug use several hours beforehand.
"I think it picks up recent usage, so a week or so ago - no. But if you smoked up the night before and you're out on the road in the morning, then it will pick it up."
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