Vincent Browne, in yesterday's Irish Times, might have more carefully worded his article on my dispute with the Northern Ireland authorities over their attempts to force me to surrender journalistic notes had he read what I have written or listened to what I have said on the matter.

He essentially argues that I should hand over this material, not least because the central character, William Stobie - a former paramilitary now charged with the murder of Pat Finucane - was identified in my articles and that the issue of journalistic confidentiality is not at stake.

He is right about confidentiality but that is not the issue. The issue goes beyond merely revealing a source; it is about the protection of sources in the broadest possible sense and about the ability of the media to act as a watchdog in a democratic society.

The detectives from the Stevens team want me to surrender my notes as the first part of a process which would conclude with me in the witness-box giving evidence against Mr Stobie as part of the prosecution array. The matter would certainly not end with me handing over my notebook to the police, as those detectives have made clear in various court hearings.

To end up giving evidence against Mr Stobie or any other source - or even placing myself in a situation where such an outcome was possible - would amount to a betrayal of a source far more serious in its implications than just revealing the name of that person.

When I first sat down with Mr Stobie in 1990 to discuss his allegations it was on the basis of an implicit contract between us. First, I would not write anything without his say-so. Second, there was an understanding that I would behave only as a journalist when using the material, i.e. I would disseminate it only in the media. The same accord underlies relations between all journalists and all sources.

Had Mr Stobie known I would hand over the interview notes to the police or allow myself to be used as a prosecution witness against him, he would never have talked to me, and who would have blamed him? Serious allegations about the Finucane murder, which Vincent Browne concedes are "explosive", might never have seen the light of day.

If I were now to hand over these notes, the message would be clear. On a personal level, no source would be able to trust me again and, effectively, I would be unable to work as a journalist. Vincent urges me to forget about my principles and get back to journalism. He does not realise that if I were to abandon my principles that would be an impossibility.

On a wider level I would be setting a dangerous precedent for other journalists, whose ability to resist similar court orders would be seriously weakened. Sources everywhere would think twice before revealing confidential information to reporters. The flow of information so vital to the media in its watchdog role could slow down; scandals would go unexposed, political corruption would thrive and state agencies might even collude in murder, confident their activities would never be revealed. And what, one wonders, would happen to whistle-blowers in Vincent Browne's scheme of things?

The chilling effect of all this on the media is why, Vincent, it is not the job of journalists to do the work of the police. This is why I cannot and will not hand over my notes to the Stevens team.

Back in 1982 Vincent Browne conducted a famous interview with the INLA leader, Dominic McGlinchey, whom he identified as his source in a subsequent article detailing McGlinchey's role in a widespread catalogue of violence.

ARE we to take it that he would have, had he been requested, followed his own implicit advice to me and handed over his notes to the police? Would he have given evidence against McGlinchey in court? What about current sources who confide information to Vincent Browne? Would he be as ready to assist the police or courts against them as he suggests I should with Mr Stobie? I think we, and more especially they, should be told.

The Vincent Browne who helped bring me into journalism some 20 years ago would, I believe, have had no doubts about this affair. Far from penning articles implying that journalists should betray their sources to the police, he would have been white with fury at the very suggestion.

Indeed, I suspect his reaction back then to a court order being served against one of his reporters would have been to redouble his investigation into the Finucane killing, and damn the consequences. The Vincent Browne of today I do not recognise. I can only hope that he has adopted this stance, not because he really believes in it but because of his characteristic and often entertaining wish to be deliberately perverse on so many issues.

Vincent mentions the level of support I have received from the Sunday Tribune, The Irish Times, other newspapers, the NUJ and "media celebrities from New York", as he terms them. I am extraordinarily grateful for this support but it raises the question: how is it that they can all clearly see the issues involved and Vincent Browne cannot?

Ed Moloney is Northern Editor of the Sunday Tribune