David Cameron commissioned the Leveson inquiry into press standards in July 2011. It followed allegations of phone-hacking at the News of the World. Among them were claims that the voicemail messages of missing teenager Millie Dowler may have been intercepted by staff at the paper.
The allegations from the Dowler family brought to a head a wave of complaints from politicians and celebrities who claimed their voicemails had also been tapped into.
On July 13 2011 Lord Justice Leveson was named to lead the inquiry. Just days earlier, the News of the World was shut down.
The inquiry was asked to make recommendations for the following:
A new more effective policy and regulatory regime for the Press
It should support the integrity and independence of the Press and media plurality
Encourage the highest ethical and professional standards
The inquiry considered the contacts and relationships of national newspapers with politicians and the police. It also looked at the extent to which the regulatory framework has failed and whether there was a failure to act on previous warnings about media misconduct.
The most controversial issue facing Lord Justice Leveson is whether the Press should carry on self-regulating, or whether the industry should instead face a new form of statutory regulation, enforceable by law.
British newspapers have regulated themselves since 1953. Back then, the Press Council was set up, but there were complaints about breaches of privacy and lack of redress. The Calcutt Review was established to examine press regulation.
In 1991 the Press Council was replaced by the Press Complaints Commission. But it quickly came under fire for having insufficient powers. Its biggest sanction is to issue a critical adjudication which the paper must publish with "due prominence".
An opinion poll for campaign group Hacked Off suggested in October that there was strong public support for an independent press regulator backed by law. 78% of those questioned by YouGov backing this option.
Hacked Off, which represents many alleged victims of hacking, argues that voluntary self-regulation has failed and calls for a new system of regulation independent of both the industry and the Government.
The Press is strongly opposed to statutory regulation and warns it could put newspapers' independence at risk.
In a television interview in October David Cameron said he did not want "heavy-handed state intervention" in the activities of the Press.
This week's report is just part one of Lord Justice Leveson's inquiry. Part two can't get underway until the police investigations and court cases have finished. That is due to look at specific allegations surrounding the News of the World and other media organisations.
But even Lord Justice Leveson has raised questions over whether there will be "any value to be gained" by going ahead with part two, given that it will not take place for a considerable time and the issues involved may have been settled by then.