By Duncan Walker
BBC News Online
The death of Dr David Kelly has put the spotlight back on the BBC 's refusal to name its source for the story that an Iraqi weapons dossier was "sexed up".
David Kelly denied being the main source of the BBC story
The weapons expert had been identified by the government as a contact of journalist Andrew Gilligan and the main source of his story - the latter a claim questioned by the BBC and denied by Dr Kelly himself.
Mr Gilligan made a second appearance before a Commons committee, which said journalists should be forced to name sources if speaking under Parliamentary privilege.
It is a demand likely to alarm many journalists, who are expected to honour a long-standing tradition of protecting those who come forward with information.
No case has provoked more interest than that of 'Deep Throat', who tipped off journalists about the Watergate scandal in 1973 and has never been formally identified.
Mr Gilligan's refusal to name his contact is one of many other examples of journalists standing by their sources - with reporters and their employers often finding themselves the subject of expensive legal actions.
Jeremy Dear, general secretary of the National Union of Journalists, said "whistleblowers" must be protected as they "will not come forward if they think they are going to be grassed up at a later stage".
He called on reporters not to be swayed, arguing that one of the key roles of journalists was to expose wrong doing and bad practice by public institutions and big corporations.
"For that reason it is the golden rule of journalism that we don't betray our sources and are prepared to go to prison to uphold that principle," he told BBC News Online.
"It is not our job to act as information providers for state institutions. They have thousands of people employed to do that work."
It is a position backed by Robin Ackroyd, who was ordered by the High Court to say who gave him medical information about Moors murderer Ian Brady, which he used in a story for the Daily Mirror.
Medical documents about Ian Brady are at the centre of one case
Mr Ackroyd, who won an appeal against the decision but still faces an ongoing legal battle, said: "Journalists protect their sources because they have a professional duty of confidence to them.
"It is not a standpoint we take because we are being difficult or precious."
The freelance journalist said Andrew Gilligan deserved the support of the media and the public and that the Commons committee had been naive to expect him to name names.
He said: "Journalists must stand their ground. And they do stand their ground.
"I have never had one iota of doubt about my own
position. I simply have no dilemma.
"I do not reveal confidential sources of information as
an overriding matter of conscience."
Last year journalists were also forced to protect their sources under questioning at the Bloody Sunday inquiry into the events of 30 January 1972, when 13 civilians were shot dead by British army soldiers. A 14th person died later.
BBC reporter Peter Taylor refused to reveal several republican, British Army and police sources to the investigation
Mr Taylor said: "My motivation is simply my wish to preserve my ability to carry out my duties as a journalist and to protect those who have assisted me in the past."
Under cross examination at the inquiry, former Sunday Times reporter Derek Humphry refused to reveal the identities of two republicans.
They were the head of the Bogside IRA and a woman who was reported to be at a hastily arranged meeting of Provisionals when the shootings on Bloody Sunday started.
But journalists are not always able to defend their sources
Sarah Tisdall famously received a six-month jail sentence in 1983 after the Guardian named her as the source of its story about the arrival of Cruise Missiles in the UK.
She had been a clerk in the office of the Foreign Secretary Michael Heseltine and had passed documents on to the paper.
The paper named her after it was ordered by a court to reveal its contact.
Ms Tisdall ended up spending four months in prison.