MPs will later attempt to implement the second stage of the Leveson inquiry into press standards in a Commons vote.
The inquiry, set up by David Cameron after the phone hacking scandal, was due to examine relations between journalists and the police.
But the government axed it in March, saying the media had cleaned up its act and it would harm press freedom.
MPs are bidding to overturn that decision in a vote on an amendment to the Data Protection Bill.
The amendment, tabled by former Labour leader Ed Miliband, is understood to have enough support to potentially inflict a defeat on the government.
It proposes launching a new, judge-led inquiry into alleged data protection breaches by national newspapers and other media companies, within three months of the bill becoming law later this year.
The inquiry would also look at:
- the extent of unlawful or improper conduct at media companies
- corrupt payments to the police
- the use of personal data
- the spread of “false news” by social media companies
It would also review the law on the treatment of crime suspects by the media, including the practice of naming them “prior to any relevant charge or conviction”.
Gerry McCann, who gave evidence to the Leveson inquiry about the coverage of his missing daughter, Madeleine, said: “Although we agree with the Leveson recommendations, they haven’t actually been implemented.”
If Leveson was not implemented “in full”, including part two, it would be “a betrayal of the victims” because there had been “no individual or corporate accountability” in the media since the report had been published in 2012, he added.
Ed Miliband told BBC Radio 4’s Today programme the behaviour of a “minority” of the media in the wake of last May’s terror attack in Manchester, highlighted by the Kerslake report, showed a new inquiry was needed.
And he said MPs had made a promise to the victims of phone hacking and press intrusion that the second part of Leveson would be implemented.
He said it would include measures for “low-cost” mediation to avoid costly legal battles.
But local newspaper groups said the “draconian” measures would still cause irreparable damage to the industry.
Alan Edmunds, editorial director of Trinity Mirror Regionals, which publishes more than 240 regional titles, said: “We do not want our journalists facing the spectre of Leveson Two when attempting to report on the activities of public figures, entirely legitimately and in the public interest.
“Another huge inquiry would only embolden those who would rather keep their activities hidden from scrutiny.”
Press regulation post-Leveson
- Lord Justice Leveson (pictured above) was appointed in 2011 to carry out an inquiry into press standards, following the phone-hacking scandal
- In his original terms of reference, it was envisaged the inquiry would be split into two parts
- A royal charter on press regulation was granted in 2013, incorporating key recommendations from the 2012 Leveson report
- A small number of publications have joined Impress, the state-backed self-regulatory body set up to be “Leveson-compliant”
- Most newspapers have signed up to Ipso, the Independent Press Standards Organisation, which has no intention of applying for recognition under the royal charter
A second amendment to the Data Protection Bill would see the introduction of a measure requiring all publishers not signed up to a state-backed regulator to pay their own and their opponent’s legal costs in relation to alleged data breaches.
The requirement to pay costs – which was tabled by Labour deputy leader, Tom Watson – would stand even if the publisher won.
Guardian News and Media, owners of the Guardian and the Observer newspapers, said this would “further erode press freedom and have a severe chilling effect for the news environment in the UK”.
It said the amendment’s proposed exemption for newspapers owned by not-for-profit trusts “has been widely interpreted as ensuring that news organisations structured along the lines of the Guardian and the Observer should be excluded from the scope of the broader clause”.
But it added: “This clause was not discussed with Guardian News and Media . And we disagree with attempts to impose a selective sanction on the media.”
Prime Minister Theresa May is against “Leveson part two”.
She had told the cabinet it was “very important for the government to resist amendments which could undermine our free press”, said her official spokesman.
Mrs May had said establishing another costly and expensive public inquiry would not be a “proportionate” solution to allegations that had already been the subject of several extensive police investigations or continuing investigations by the Information Commissioner’s Office, the spokesman added.