High Court Justice Lester Chisholm has ordered Anglican authorities to halt further demolition work on Christ Church Cathedral.
The judicial review was taken by the Great Christchurch Buildings Trust chaired by Rich Lister and former MP Phillip Burdon, and ex-MP Jim Anderton.
They alleged that plans to demolish the cathedral breached the Act of Parliament which protects it.
Justice Chisholm ordered that the Anglican Church Property Trust must rebuild on the site.
But he also ruled that the church was not required to build a replica.
The result is likely to be a mix of a partly restored old cathedral with new elements.