Official papers show more than 100 convictions have been secured under the year-old drug driving legislation.
Figures obtained under the Official Information Act reveal that 305 field tests were done on drivers thought to be under the influence of drugs in the first 11 months after the Land Transport Amendment Act came into force.
From these, 216 charges were laid for drugged driving offences and 129 convictions secured.
Another 87 cases were still before the courts, as at 30 September.
Transport Minister Steven Joyce says the drug driving legislation is working as intended.
But the Automobile Association says the figures show the new laws are woefully inadequate, and thousands of impaired drivers are slipping through police checkpoints.
AA motoring affairs general manager Mike Noon says a driver has to be showing significant impairment and to have passed an evidential breath test to be tested.