Justice Minister Simon Power is defending a provision in proposed new liquor laws allowing police to arrest people for breaching a liquor ban.
The legislation will have its first debate in Parliament on Thursday.
Attorney General Chris Finlayson has warned the arrest rights police will be given under new laws go too far.
He says several provisions are inconsistent with the Bill the Rights, but the new arrest power, for people who breach alcohol bans, is the most serious.
He says a liquor ban breach would be an infringement offence and not serious enough to warrant arrest. Police already have the power to arrest people when it is necessary to maintain public order.
But Mr Power says police say they also need it to properly enforce liquor bans.
The Green Party says it too has grave concerns about the extension of police powers.
Co-leader, Metiria Turei, says the police already have sufficient powers to deal with excessive alcohol use and believes the bill should target cheap alcohol and excessive marketing.
A vote on the drinking age will not be held until the legislation returns to Parliament following public submissions.
