Two journalists have won permission to challenge the legality of search warrants issued during an investigation into the suspected theft of documents from the Police Ombudsman's Office.
Barry McCaffrey and Trevor Birney were arrested, questioned and released last August.
The confidential documents relate to a police investigation into the murder of six men in Loughinisland.
Mr McCaffrey and Mr Birney produced a documentary about the 1994 killings.
It was reported at the time that the ombudsman reported the suspected theft of the confidential files to the police.
Lawyers representing the journalists and Fine Point Films, the company behind the film 'No Stone Unturned', contend the warrants did not cover all of the material seized.
In Belfast High Court on Monday, the pair were granted leave to seek a judicial review on all grounds of challenge - including a claim that relying on the Official Secrets Act to obtain the warrants was incompatible with their freedom of expression rights under European law.
Police have already given an undertaking not to examine any of the seized documents and computer equipment pending the outcome of proceedings.
The case will be heard over three days in May.