The ruling allows thousands of Canterbury home owners, to proceed with a class action against the government insurer Southern Response.
The decision is the final chapter in a legal battle over whether the class action would proceed on an "opt-in" or "opt-out" basis.
While Southern Response argued for an opt-in approach, lawyers for the class action believed it should proceed on an opt out basis - one in which all policyholders would be included.
Class action representative Grant Cameron says the decision is hugely significant for future class actions.
He says it will ensure New Zealanders get proper access to the justice they deserve.