Lawyers for Kim Dotcom say the internet businessman is likely to fight a Court of Appeal ruling that search warrants used to raid his house near Auckland were lawful.
The decision made public on Wednesday overturns a ruling by Chief High Court judge Justice Winkelmann in June 2012 that the warrants were too broad and therefore unlawful.
Police carried out search warrants on the properties of Kim Dotcom and Bram van der Kolk on 20 January 2012 and seized some 135 electronic items. The warrants were executed under the Mutual Assistance in Criminal Matters Act 1992 at the request of the US Department of Justice.
The United States is is seeking the extradition of Mr Dotcom, Mr van der Kolk, Mathias Ortmann and Finn Batato on a number of charges, including breach of copyright and money laundering.
Crown lawyers argued at a hearing in November last year there was enough information in the application for the warrants to make it clear what police were looking for.
The Court of Appeal judges accepted that, saying the warrants were defective in some respects, but there was no miscarriage of justice.
It concluded that Mr Dotcom and the other respondents would have understood the nature and scope of the warrants - especially in light of their arrest warrants - which were not defective and explanations given to them by police when the properties were searched.
However, the appeal has been only partially successful. The court ruled that a decision to send copies of material seized to authorities was a breach of agreements.
On 16 February 2012, the Solicitor-General gave a direction to the Commissioner of Police under the Mutual Assistance in Criminal Matters Act 1992 that the items seized on the searches were to remain in the "custody and control" of the Commissioner until further direction.
In deciding that the removal of the clones (copies) of the electronic items from New Zealand to the US was not authorised, the court said it was satisfied the Solicitor-General's direction applied to the copies and that their removal was therefore in breach of the terms of the direction.
A lawyer for Kim Dotcom, William Akel, says it is disappointing that the warrants have been ruled lawful and any appeal has to be lodged within 20 working days.
"One always prefers to succeed in any appeal, but the important point now is that we have to consider and analyse the decision in some detail, and consider an application for leave to appeal to the Supreme Court."
Crown Law on Wednesday declined to comment on the ruling.
Kim Dotcom is suing police and the New Zealand Government's spy agency for $5 million compensation, arguing that the raid in 2010 was illegal and officers used unnecessary force.
Mr Dotcom tweeted online on Wednesday that he's "not sorry that fighting back, getting up and being successful are encoded" in his DNA, and he's happy he can "challenge evil".
No quick decision - PM
Prime Minister John Key is not expecting any quick decision on the extradition Kim Dotcom despite the Court of Appeal ruling.
Mr Key said on Wednesday there are likely to be many twists and turns in the case and he is certain it will not be resolved before this year's election.
"It's a very long process. I mean, if somebody wants to appeal an extradition and take legal action at every nook and cranny, it can take a very long time."
Mr Key said he cannot say much more about the matter, given it is likely to be subject to further legal arguments.
One of Kim Dotcom's smaller creditors says it's frustrating seeing him making big, bold claims about backing new ventures when they still haven't been paid what they're owed.
A number of companies have not been paid for work at the Dotcom mansion at Coatesville, north of Auckland, more than two years after the raids which sparked the high profile extradition battle.
Donna Richmond from Auckland Inground Pools told Radio New Zealand's Morning Report programme she is owed about $5000.
"It's not going to break our business, but morally it's just something that we need to be paid, that could have paid a few bills that we would have struggled through otherwise - we're just a small business."
Ms Richmond says she will just have to take Mr Dotcom at his word, when he says he's going to pay back all his creditors back.