A court ruling that search warrants police used in a raid on internet tycoon Kim Dotcom's house were invalid is "embarrassing" for police, a member of the law society says.
The German national was arrested after police swooped on his home in January confiscating hard drive data among other personal possessions.
Justice Helen Winkelmann yesterday found the warrants did not adequately describe the offences to which they related.
"Indeed they fell well short of that. They were general warrants, and as such, are invalid."
Convener for the criminal law section of the Law Society Jonathan Krebs told TV ONE's Breakfast this morning the ruling was "a little bit embarrassing" but said it was a good example of the police being pulled up for acting unlawfully.
"It is a really good example of the law working properly in the sense that they can be challenged and the police can be brought up on their tracks."
Krebs said it was not unusual for warrants to be challenged, such as in cases where drugs were involved, but it was unusual for the warrants to be found invalid.
"The most recent public example of that is the Urewera raids, where a significant chunk of the evidence was found to be illegally obtained and not admissible."
Dotcom's lawyer Ira Rothken said the New Zealand police were pressured by the United States to act quickly on the Megaupload founder.
"Not only did the NZ police come in and break down the door to Mr Dotcom's house, throw his family out, seize just about every type of digital media in his house...they are also involved in aiding and abetting the US taking these hard-drives offshore, in a hurry, before the court could even rule on it.
Krebs said even though the Government was required to co-operate with the US under the Mutual Assistance and Criminal Investigations Act, NZ should still have approached the matter with caution.
"There's something to be learned about how NZ should, despite whatever pressure is imposed, nevertheless take time and reflect a little more carefully on warrants."
Winkelmann also ruled it was unlawful for copies of Dotcom's computer data to be taken out of the country, and any cloned items or copies are not permitted to leave New Zealand.
She instructed the Attorney-General to return any clones or copies of the hard-drives held by New Zealand police.
An independent lawyer will now review the seized items and determine which are relevant to the investigation. Relevant items will be provided to US authorities and the rest will be returned to Dotcom.
Krebs hoped the US would comply with the ruling to voluntarily return the confiscated items.
"I think a superior in the court in NZ should have sway in America in terms of the relationship between the two countries."
Last night a spokesman for Dotcom said the alleged internet pirate was "pleased", but he would not be making any further comment on the decision as appeals were likely.