The National Party is trying to drive a wedge between two ministers over their positions on whether to introduce roadside saliva testing for drugs.
Yesterday, RNZ revealed the minister responsible for road safety has major concerns about saliva testing motorists for drugs, despite her own officials recommending it.
They told the associate Transport Minister Julie Anne Genter that the current method of detecting drugged drivers was ineffective and argued that random roadside saliva testing should be introduced.
But Ms Genter has made it clear she has major concerns about the technology saying it is expensive, intrusive and that the current method of detecting drugged drivers is extremely effective.
"We already have an extremely effective impairment test which is over 90 percent effective usually backed up by 100 percent accurate blood tests," Ms Genter said.
Police currently carry out a roadside impairment test on motorists they suspect are driving under the influence of drugs, where the driver carries out a series of coordination tests. If they fail the test they are then blood tested.
During Parliamentary Question Time yesterday, National's police spokesperson, Chris Bishop, asked her about recent comments made by the Police Minister on the matter.
"Why does she stand by her statement on Radio New Zealand this morning that 'I have some concerns about roadside saliva testing' when a ministerial colleague Stuart Nash has said 'we should be looking at it and I think it has got to be rushed out'?"
But Ms Genter responded that the different views were not mutually exclusive.
"I have concerns about it and we are looking into it. We need more evidence if we're going to be sure that we are spending money in the most effective way to deal with the problems that are caused by impairment," she told Parliament.
Ms Genter's colleague, Green MP Gareth Hughes, then ran interference asking how many other jurisdictions conduct roadside saliva testing.
"Only two jurisdictions currently conduct roadside saliva testing and what we know about roadside saliva testing is that it is unable to test for a wide variety of substances that may cause impairment," Ms Genter responded.
"Also, it costs significantly more than alcohol testing does, $30 to $40 per test as opposed to several cents for alcohol screening."
The Transport Ministry has refused to make anyone available for an interview on its controversial advice to the minister this week.