ACT Party Leader David Seymour has scored a win on his Rugby World Cup bar Bill.

MPs have backed the first reading of his Bill that will allow bars to be open during the Rugby World Cup, though the full extent and scope of allowed trading is still to be finalised.

Mr Seymour said his Bill is ultimately about whether we take a permissive approach to responsible adult New Zealanders being able to choose their own values, their own behaviour, and what is important to them.

"I'm very proud that some of the details of the bill will be able to be debated as we constantly seek to refine that balance between freedom and harm."

The Green Party's chosen to take a pragmatic approach to the legislation loosening liquor licensing laws around the Rugby World Cup.

Originally the Greens blocked the Bill but MP Kevin Hague said the fact the legislation was going to proceed in some shape or form anyway means they've had to see what they can extract from the process.

"Through the stance that we took yesterday and the negotiation that we've had both with David Seymour and the Government, we are now confident that as a result of our actions this Bill will be substantially improved."

Meanwhile Associate Minister of Health Peter Dunne doesn't see the law change as causing potential health problems.

"This is very time limited and specific and I thin kit's logical in the public interest."