All the evidence US authorities have against Kim Dotcom doesn't have to be released to his legal team, the New Zealand Supreme Court has ruled.
The court's decision was released on Friday after eight months of going over the case Dotcom, Finn Batato, Mathias Ortmann and Bram van der Kolk brought against the US and North Shore District Court.
The US is trying to extradite them so they can be tried on charges alleging the file-sharing Megaupload website illegally netted them more than $US175 million ($A194 million).
In the Supreme Court hearing in July last year, they argued they should be able to see all the evidence in the US government's case against them, rather than just the provided summary.
Dotcom's lawyer Paul Davison QC told the court the summary was inadequate, made propositions and didn't include any evidence showing criminal intent.
But New Zealand's Solicitor-General Mike Heron said a local court doesn't have the power to order the US - a foreign state - to hand over anything.
Any disclosure would also be lengthy and difficult, he said.
The FBI seized a huge number of files and emails, but needs passwords to get at encrypted files. It has offered to provide Dotcom with clones of the files in exchange for the passwords.
German-born Dotcom was arrested in 2012 following a raid on his mansion north of Auckland.
He is also going to the Supreme Court to try to overturn a Court of Appeal ruling the raid was legal, despite a lower court saying police search warrants were too vague.
