Police have netted over 400 drug drivers since the Land Transport Amendment Act was introduced in November 2009.
More than half were under the influence of cannabis, with more than methamphetamine or BZP the next most common drug used.
Figures released to The Dominion Post show 514 people appeared sufficiently impaired for police to perform a drug test, stuff.co.nz reports.
If police believe a driver to be under the influence, the law allows them to carry out an impairment test, which measures co-ordination and physiological reactions.
Of the 514 drivers tested, 455 were unable to take nine steps in a straight line, having to use their arms for balance, miscounting the number of steps, or simply failing to understand the instructions.
The drivers were also checked for slurred speech, dilated pupils, and flushed or clammy skin.
Of the drivers who failed the test, 429 tested positive for drugs. Driving while impaired carries similar penalties to drunk-driving, and the majority of those caught were disqualified from driving and given a fine or community work.
Six were given home detention and 15 received jail sentences.
The Land Transport Amendment Act 2009 will be reviewed this year, while police are investigating the effectiveness of drug tests being developed overseas.
3 News