There are few absolutes in journalism. Journalists cannot even agree if what they do is a profession, craft or trade, but there is one thing they do agree on, that a journalist should never reveal confidential sources.

Ed Moloney, the Northern Editor of the Sunday Tribune, has been asked to hand over interview notes to RUC detectives investigating the murder of the Belfast solicitor, Mr Pat Finucane. He has refused and is to appear in court next week.

The reason for Mr Moloney's refusal is the same as that of all journalists who have refused to name their sources. To do so would make it impossible for journalists to act as a watchdog in the public interest.

The public has to know, the rationale goes, so members of the public can always trust a journalist not to identify them if they give information concerning a wrong.

Codes of ethical conduct insist that journalists never reveal sources. This works for both journalist and source. This principle is the reason human-rights groups and journalists' organisations have protested at the treatment of Mr Moloney.

Journalists have no legal right to protect their sources. In recent years, however, the courts have been loath to ask them to name their sources simply because it is well known they will refuse.

Two journalists have been jailed in this State for refusing to identify sources, Joe Dennigan of the Irish Press in 1934 and Kevin O'Kelly of RTE in the early 1970s.

More recently Susan O'Keeffe, who made the World In Action programme that led to the beef tribunal, was prosecuted for refusing to name her sources. She was acquitted on a technicality.

Three years ago Barry O'Kelly, a reporter with the Star, refused to reveal his sources to a judge. However, the Attorney General's office announced that the law had developed since Kevin O'Kelly had gone to prison. This development was in the light of rulings of the European Court of Human Rights in an important judgment concerning a British journalist, Bill Goodwin. The court ruled that forcing journalists to reveal sources was contrary to Article 10 of the European Convention on Human Rights, which protects freedom of expression.

It said that compelling disclosure of the source was not necessary in a democratic society; that protection of confidential sources was an essential means of enabling the press to perform its important function of public watchdog; and should not be interfered with unless in exceptional circumstances where vital public or individual interests were at stake.

Even though journalists would be put in danger if they identified sources in an environment as volatile as Northern Ireland, this has not stopped the authorities seeking the identification of sources. In 1992 Channel 4 and the Box Production company were fined £75,000 for refusing to reveal their sources for a programme on loyalist death squads. Earlier Bernard Falk of the BBC spent four days in a Belfast jail for refusing to confirm to a court that the IRA man he had interviewed was the man in the dock.

The importance of protecting the identity of sources is not just a journalist conceit or a piece of special pleading. The European Court of Human Rights has ruled on the "importance of protection of sources for press freedom in a democratic society" and of the "chilling effect" of ordering source disclosure.

In the US a source who was identified took a journalist to court which ruled that the journalist was in breach of contract, while in Sweden senior civil servants are precluded from even investigating who might have leaked information.

Michael Foley is a lecturer in journalism at the Dublin Institute of Technology and a media commentator