Kim Dotcom's case is back in court today where legal arguments are happening behind closed doors.

The hearing, before Chief High Court judge Justice Helen Winkelmann - is taking place in a conference room at the High Court in Auckland, and is closed to members of the public and media.

The next major hearing in the Dotcom case is set down for mid-April when evidence about the raids on his Coatesville mansion will be debated.

An extradition hearing in August will decide if the internet mogul and three other accused will be flown to the US to face charges of copyright infringements, online piracy and money laundering through their Megaupload file sharing website.