Transport Minister Steven Joyce has promised to take another look at drink-driving laws amid concerns a loophole allows serious offenders back behind the wheel without any assessment or treatment after their disqualification period ends.

Convicted drink-drivers given an indefinite licence suspension can apply to have their licences returned after a year and a day - but have to undergo an alcohol and drug assessment and liver tests. If they fail, they must complete treatment.

However, a New Zealand Transport Agency spokesman confirmed to the Dominion Post no assessment was needed for people who had completed disqualifications for a specified period - a sentence which is still often applied to those guilty of more serious offending.

Wellington alcohol counsellor Roger Brooking discovered the anomaly after a repeat drink-driving client was automatically granted his licence back after a two-year disqualification - even though it was his third offence.

Mr Joyce said he was aware those who committed minor offences did not necessarily have to undergo alcohol and drug assessments, but had not realised that could also apply to more serious offenders.

"It's a point worth reviewing as to whether mandatory alcohol and drug assessment needs to be widened."