The Government may not be up for an argument about the Crown's sovereignty, but the Greens are.

A landmark decision from the Waitangi Tribunal has found Maori leaders didn't cede sovereignty to the Crown when they signed the Treaty.

Greens Treaty spokeswoman Catherine Delahunty says there's a great deal of separation in New Zealand already, so she doesn't see a problem with setting up a dual governance system.

"Pakeha people for example don't actually live a Maori and Pakeha life. Most Pakeha people live very much as if they were the only nation here, and it's not true."

The Government insists it changes nothing for present-day New Zealand, but Ms Delahunty disagrees.

"It really isn't a scary thing, and it doesn't create anymore division. We've got more division by denying our history than we have by acknowledging our history."