NZ breathalysers fail the test, says National MP

Built-in tolerance levels in police breathalysers are letting some motorists get away with drink-driving.

National law and order spokesman Simon Power said the public would be shocked to know that drivers could be 10 per cent more drunk than their breath tests showed.

"We've always been told the limit's the limit," he told the Dominion Post newspaper.

The legal limit is 400 micrograms of alcohol per litre of breath for adults on a full license, and 150mcg for those aged under 20.

But New Zealand breath-tests will not return a positive result unless drivers have 440mcg or 170mcg in their breath.

However, National road policing manager Superintendent Dave Cliff said the tolerance levels enabled police to be "absolutely sure" that a person was over the limit to ensure a prosecution would stick.

Police carry out more than two million breath tests a year.

- NZPA