The Leveson Inquiry into press standards formally starts today amid concern witnesses with incendiary evidence will have their statements curtailed.
The judicial investigation at the Royal Courts of Justice in London will begin with opening addresses by Robert Jay QC, the inquiry's barrister, and counsel representing more than 50 core participants, including media groups and victims of phone-hacking by the News of the World (NOTW).
Among those granted core participant status are the parents of murdered schoolgirl Milly Dowler, former British Army intelligence officer Ian Hurst and the former head of international motor sport, Max Mosley.
Lord Leveson last week rejected a request by police and the Crown Prosecution Service (CPS) to vet evidence heard by the inquiry to ensure it does not prejudice future criminal trials.
However, he said the hearings would not be used by witnesses as a public platform to "pillory" others.
One lawyer representing several core participants told The Independent: "There are serious matters which should be in the public domain and we should not have a situation where a witness is perhaps only allowed to partially air their concerns."
The difficulty the inquiry faces is highlighted by the blame game gathering pace away from the inquiry's authority.
Following the second appearance of James Murdoch before the Commons culture committee last week, an account of a alleged meeting between two News International senior executives, which was quoted by the Labour MP Tom Watson, has been challenged as incomplete and inaccurate.
Mr Watson shocked his committee colleagues when he said he had recently spoken to the NOTW's former chief reporter, Neville Thurlbeck. An email sent to Mr Thurlbeck, known as "For Neville", has become a key piece of evidence that revealed the extent of hacking inside the paper.
Mr Watson claimed Mr Thurlbeck told him about a conversation he had in 2008 with Tom Crone, former News International legal manager. According to Mr Thurlbeck, he and Mr Crone talked about how much Mr Murdoch needed be told about the key email. Mr Watson said this revealed Mr Murdoch knew more than he admitted.
However, over the weekend, Mr Thurlbeck, who was arrested earlier this year and is on police bail over matters relating to the illegal interception of voicemails, claimed Mr Murdoch had told the truth and that when he was NI's executive chairman "he had been kept in the dark and deprived of vital evidence".
Mr Thurlbeck said he told Mr Watson of another NI executive involved in commissioning hacking. He also alleges he told Mr Watson of a dossier of illegal newsgathering he had pulled together about the "chronic lack of full disclosure" inside NI. He said: "Regrettably, Mr Watson failed to mention all this."
Q&A the task for Leveson
Q: The phone-hacking scandal has meant people have lost trust in the UK's printed media. Will Lord Leveson's inquiry change that?
A: Although tasked with looking at the culture, ethics and practices of British newspapers, it might all come down to how they are regulated. Most expect a tighter regime.
Q: What happened inside the News of the World means everyone gets tarred with the same brush, right?
A: Yes and no. Leveson can't look too deeply into criminal wrongdoing at the now defunct tabloid. That's the job of a criminal court, not an inquiry ordered by Downing Street.
Q: The inquiry's remit includes media "practices": so he'll have to look at what went on – and that means "illegal" practices in anyone's book?
A: It does. But don't expect too deep a look. There have been 14 arrests, and inquiries are continuing.
Q: Look, is there going to be any Fleet Street blood on the carpet?
A: Certainly not. This is a British judicial inquiry.
Q: But over 50 victims have been lined up. They expect their day in court: "revenge" and "getting even" spring to mind
A: Revenge might have to wait. Part two of the inquiry will start only after all criminal proceedings have ended – only then will there be a serious probe of News International.
Q: So how long will all this take?
A: Lord Leveson himself has hinted it could be years.