Kim Dotcom's battle against copyright allegations has been dealt a blow after New Zealand's Court of Appeal ruled search warrants used in a raid of his mansion were valid.
The decision overturns a 2012 High Court ruling that declared the warrants invalid because they weren't specific enough and did not properly describe his offences.
The warrants preceded Dotcom's arrest and were used to seize 135 electronic items including laptops, computers, hard drives, flash sticks and servers in January 2012.
The Attorney-General appealed the 2012 High Court decision, arguing that a reasonable person could have understood the warrants despite ambiguities.
The Court of Appeal on Wednesday agreed, ruling while the warrants were defective in some respects, the defects were not large enough to render them invalid.
It ruled no miscarriage of justice had occurred.
"We are satisfied that the defects in the search warrants have not caused any significant prejudice to the respondents beyond the prejudice caused inevitably by the execution of a search warrant," the judgment said.
No more items were seized than if the warrants contained no defects, the Court of Appeal ruled.
The raid was performed at the request of the US Department of Justice, which is trying to extradite Dotcom and his three co-accused, Finn Batato, Mathias Ortmann and Bram Van der Kolk, on criminal copyright violation and racketeering charges.
The charges relate to the quartet's running of now-defunct file-sharing website, Megaupload.
While the Court of Appeal overturned the decision on the validity of the warrants, it did agree with the High Court that clones of Dotcom's material should not have been taken to the United States.
Forensic clones of electronic items were made and handed to the FBI, which took them to the United States in March 2012.
The Court of Appeal ruled the removal of the clones was a breach of the direction of the Solicitor-General.
It found while Solicitor-General Michael Heron had the power to allow the cloned items to be taken out of the country by the FBI, he did not direct it.
Dotcom and his co-accused are fighting extradition to the United States to face charges.
They are also fighting in the Supreme Court for full disclosure of the US's case against them.
Late in 2012, New Zealand Prime Minister John Key admitted pre-raid spying on Dotcom by the Government Communications Security Bureau (GCSB) was illegal because Dotcom was a New Zealand resident.
The government passed amendments to the laws governing the GCSB in August.