Megaupload founder Kim Dotcom is seeking a judicial review, arguing that a warrant used to seize electronic items from his New Zealand home was illegal and deficient.
The items, along with other evidence, led to the arrest of Mr Dotcom and three other men in Auckland in January this year.
All are on bail awaiting a hearing in August on their extradition to the United States to face charges of internet piracy relating to the file-sharing website. It is considered the largest copyright breach alleged in the world.
Kim Dotcom's lawyer Paul Davison, QC, told the Auckland High Court on Tuesday the warrant was so broad that it led to a wholesale sweep of nearly every electronic item in his client's house.
He said Mr Dotcom's privacy was subsequently breached, because some of the seized items contained family photos and videos.
Mr Dotcom is asking for copies of all personal information taken.
Crown lawyers late on Tuesday afternoon began arguing that it can not determine what is relevant without having the electronics accessed by forensic investigators and will continue their case on Wednesday.
The hearing is set down for two days.
Megaupload was indicted in a federal court in the US state of Virginia on 19 January and the site was shut down.