Key Points:

The Government has today defended its plans to introduce roadside drug testing for drivers.

Transport safety minister Harry Duynhoven conceded that tests were still being developed but said it was already possible to establish if a driver had been using drugs such as cannabis and amphetamines.

And he told Newstalk ZB that the beginning point in clamping down on dangerous driving was "impairment and that is already covered by the law".

Driving while impaired with illegal drugs is due to become a new offence, attracting the same penalties as drink driving.

A police officer who suspects a driver is affected can carry out an eye examination and motor skills test, which includes balance and "walk and turn".

Drivers who fail that roadside test will be taken to the police station and a doctor called in to assess whether they are "incapable" of driving.

Police National Headquarters Superintendent Dave Cliff said the "impairment" test had a lower threshold than the existing test, which measures whether a driver is "incapable of proper control".

Random tests will not be conducted but if police believe a driver is impaired they must initiate a drug test.

The roadside drug test is not compulsory under present law.

If the driver fails such a test, they will be obliged to give blood to be analysed.

If drugs are found in the blood, the driver will be charged, facing the same penalties as for drink driving.

Police cannot at present demand a blood test for drugs.

Transport Minister Annette King said the issue was complicated and "the system we have come up with best suits our needs".

"The aim of this policy is to ensure that people know if they take drugs and then get behind the wheel of a car they're likely to be charged."

Ministry of Transport figures showed drugs were suspected in 36 crashes in the year to December 31, 2005. Drugs were proven in three whereas alcohol was suspected in 383 crashes.

The Government's road safety policy statement said yesterday alcohol was a contributing factor in more than 100 fatal crashes a year.

Ms King said it was difficult to pinpoint the level of illegal drug use in drivers "because we do not routinely test for drugs".

But illegal drug use among drivers, particularly the young, was higher than the statistics suggested.

'Backdoor measure'

But Green MP and party spokeswoman on drug and alcohol issues, Metiria Turei, said the plans introduced a "Misuse of Drugs Act search using a backdoor measure".

There was a legal limit for alcohol, enabling some consumption before people were considered impaired. But the plans for drug-testing would not enable a proper impairment test.

The roadside test was "subjective" and would then lead to a blood test which was effectively "a search, but with no evidentiary basis for impairment".

The blood test would only confirm or deny the presence of drugs, not when they were taken and whether a person was affected by drugs at the time of driving.

Ms Turei said some drugs - including cannabis - stayed in a person's system for some weeks - therefore a blood test was effectively a "search on your body".

"Having a limit is fine, but having a zero limit is different."

Ms Turei believed "there is a little bit of over-hype" about the links being drawn between cannabis use and accidents.

Mr Cliff said the field impairment testing considered a range of indicators and its efficacy had been "extensively researched".

"If someone is tired or has a medical condition they won't exhibit the same signs as someone who is under the influence of an illegal drug."

Preliminary ESR research on fatal crashes indicated "a significant number [of people] have illegal drugs in their system at the times of death".

Asked how police could be sure a positive drug test meant a person was "drugged" at the time, he said the roadside test would prove that.

The Road Transport Forum has called for tougher drug tests, saying the move was urgent because of the growing use of so-called recreational drugs in the community.

Other measures announced yesterday include "no tolerance" by police of anyone travelling more than 54km/h around schools and early childhood centres.

The Government is also looking at other areas, including demerit points to target repeat and serious driving offenders.

It will look at introducing demerit points for intersection infringements, red-light cameras and for seatbelt offences.


COULD YOU PASS THE TEST?

Tests to assess whether drivers are drug impaired can include:

THE WALK AND TURN TEST:

The officer will mark a line on the road about 3 to 4 metres long. The subject will then be asked to walk along the line, turning at the top and returning.

EYE EXAMINATION:

The human eye usually dilates between 3mm and 6mm, but drug users' pupils can dilate up to 9mm. Officers can tell what type of drugs a driver is effected by judging by pupil dilation. A glazed eye is also a tell-tale sign of drug use.

MOTOR SKILLS TEST:

A driver must maintain his balance while standing upright, with his hands at his sides, head tilted back and eyes closed.

TIME DISTORTION TEST:

Stoned drivers can lose track of time. Motorists must close their eyes and estimate when 30 seconds have elapsed.

* additional reporting NZPA