Labour has demanded the revival of the Leveson inquiry to consider links between police and the press.
Shadow home secretary Andy Burnham said holding part two of the probe - suspended pending the completion of criminal proceedings - was "non-negotiable".
The comment came as Mr Burnham and shadow culture secretary Maria Eagle staged a conference in parliament to discuss the obstacles faced by campaigners against injustice.
Representatives from the Hacked Off group - which focuses on the phone-hacking scandal - and the Orgreave campaign - urging honesty about the 1984 confrontation between police and miners - were among those giving evidence at the event.
The panel - including Labour peer Baroness Doreen Lawrence - also heard from Alastair Morgan, whose brother Daniel was investigating police corruption before his murder in 1987.
Former TV presenter Jacqui Hames, of Hacked Off, said the media was once again "cosy and comfortable" with the authorities and links with the police had to be examined further.
"Leveson two will shine a light at this relationship," she said.
Mr Burnham told the meeting that reassurance was needed about the "relationship between police and press going forward".
"One of the issues we do want to touch on today is the need for that second stage going forward," he said.
He added: "Leveson two is non-negotiable."
Part two of Leveson was put on hold while legal processes were completed, but ministers are now thought to believe most of the issues have been aired and there would be little purpose reviving the inquiry.
Shadow culture secretary Maria Eagle said she was determined that Leveson be implemented in full and stage two of the inquiry go ahead.
"I think there are vested interests in government who are not particularly interested in that."
Why are you making commenting on The Herald only available to subscribers?
It should have been a safe space for informed debate, somewhere for readers to discuss issues around the biggest stories of the day, but all too often the below the line comments on most websites have become bogged down by off-topic discussions and abuse.
heraldscotland.com is tackling this problem by allowing only subscribers to comment.
We are doing this to improve the experience for our loyal readers and we believe it will reduce the ability of trolls and troublemakers, who occasionally find their way onto our site, to abuse our journalists and readers. We also hope it will help the comments section fulfil its promise as a part of Scotland's conversation with itself.
We are lucky at The Herald. We are read by an informed, educated readership who can add their knowledge and insights to our stories.
That is invaluable.
We are making the subscriber-only change to support our valued readers, who tell us they don't want the site cluttered up with irrelevant comments, untruths and abuse.
In the past, the journalist’s job was to collect and distribute information to the audience. Technology means that readers can shape a discussion. We look forward to hearing from you on heraldscotland.com
Comments & Moderation
Readers’ comments: You are personally liable for the content of any comments you upload to this website, so please act responsibly. We do not pre-moderate or monitor readers’ comments appearing on our websites, but we do post-moderate in response to complaints we receive or otherwise when a potential problem comes to our attention. You can make a complaint by using the ‘report this post’ link . We may then apply our discretion under the user terms to amend or delete comments.
Post moderation is undertaken full-time 9am-6pm on weekdays, and on a part-time basis outwith those hours.
Read the rules here