National is accusing the government of carrying out a crude power-grab over a bill setting out the mechanics for next year's cannabis referendum.

Photo: RNZ / Rebekah Parsons-King

The party is upset by a clause that allows the Cabinet to decide the question that will be put to the public for that and any other election year referendum - such as David Seymour's End of Life Choice Bill.

It says it flouts a long-standing convention that the decision is left to Parliament.

The government says the legislation is designed to help get its ducks in a row, in case there's more than one referendum next year.

The Bill also states that the question on the ballot paper will be decided by Cabinet, something National MP Nick Smith said set a dangerous precedent.

"This is a crude power grab that denies the right of Parliament and the public to have a say on the way in which elections and referendum are conducted", he said.

During the bill's first reading debate last night, Dr Smith accused Labour of hypocrisy.

"I want to remind members opposite, of what they said when we had a flag referendum.

"The Labour spokesperson said 'it is absolutely that the wording and the referendum be determined by parliament", Dr Smith said.

The government says concerns it could try to slant the cannabis referendum question are unfounded, because there will be input from the Electoral Commission and Ministry of Justice.

It also says the cross-party Regulations Review Committee could use its veto if it is worried about the wording.

But National's Justice spokesperson Mark Mitchell isn't convinced.

"I don't believe that for a minute. That will not happen, that cannot happen", he said.

Green Party justice spokesperson Golriz Gharahman said the Bill was simple, logistical legislation and National was spouting misinformation.

"There is no such thing as this breach of constitutional norm that has been cried across this House all afternoon when it comes to the setting of the question", she said.

Justice Select Committee Chairperson Meka Whaitiri said National was trying to have it both ways - because she said they had repeatedly refused to join a cross-party group on the cannabis referendum.

"We reached out to all parties in this House.

"You cannot come to this House and say you were not involved, you cannot claim an innocent position of having no knowledge, of us doing this behind closed doors", Ms Whaitiri said.

The debate was interrupted as the House broke for the week, so the Bill is still yet to pass its first reading.