The decision by gardaí to smuggle Jean Treacy in and out of court during the Eamonn Lillis murder trial – as though she was some exotic contraband in need of protection – continues to divide opinion. One side – Vincent Browne, Noel Whelan and others – argue that as an innocent, helpful witness, Treacy – or her friends and extended family – is not a legitimate target for media attention outside of her courtroom evidence. The other side – newspapers and editors, mainly, though not very many of them thus far – insist that a high-profile witness in a high-profile case cannot be held to have the same rights to privacy (in so far as those rights exist at all) as your average citizen.

So far, the Browne/ Whelan argument seems to be the stronger. There may well be compelling reasons why photo­graphers and TV cameramen should be allowed to capture images of witnesses as they walk to and from court, but the problem for the editors and journalists last week was that they didn't come up with any. By leaving the argument to people whose interest in Treacy is purely commercial, the National Newspapers of Ireland, which has met the Garda Commissioner on the subject, is fatally undermining its case and handing ammunition to those like the Minister for Justice who would welcome the kind of strict privacy law which really would undermine the ability of the media to do its job properly. (And which may come a step nearer if Treacy's impending nuptials turn into a media circus).

There is one very good reason, which we'll return to, why witnesses such as Jean Treacy should not be afforded protection, and it has nothing to do with free speech, the rights of press photographers and the need for justice to be seen to be done, all of which have been put forward – lamely – by the media side recently.

The "seen to be done" argument is perhaps the most ludicrous. The phrase originates in a 1924 dangerous driving case in England in which the clerk to the presiding judges turned out to be a member of a firm of solicitors which was suing the defendant. When he learned of this connection, the defendant appealed his conviction. Lord Chief Justice Hewart found that although the judges had made their decision in good faith, the conviction should be quashed. "A long line of cases shows that it is not merely of some importance but is of fundamental importance that justice should not only be done, but should manifestly and undoubtedly be seen to be done," he said. It's fair to assume that fragrant witnesses and paparazzi formed no part of Hewart's thinking when he coined that sentence.

In any case, how could anyone argue credibly that justice was not seen to be done to Eamonn Lillis? Perhaps only in the Catherine Nevin trial in 2000 has there been such media and public interest in a murder case. Pages of newsprint were given over to the trial every day. Newspapers sent their best colour and feature writers. The television stations were there, the radio stations were there. Rarely has a public been so well informed about a case. The absence of a current image of Jean Treacy had no effect at all on the extent of our knowledge about the case.

But she should never have been afforded the protection she was given, and neither should any witness in the future, except in the most exceptional circumstances. Her treatment set a precedent, with An Garda Síochana effectively announcing it is prepared to tolerate a hierarchy of witnesses in criminal trials. Witness A is regarded as more important than Witness B and will therefore be smuggled down an underground tunnel while Witness B is left to fend for herself against a battery of cameras outside the court house.

This is a risky business for any prosecution case, which depends on getting all its witnesses to give evidence in a clear, compelling and convincing manner. Many people are reluctant to step into the witness box and need to be persuaded that what they have to say is vital in bringing a guilty person to justice. Their better nature needs to be appealed to. If they then find out that, actually, their evidence is not as vital as they were told, not as important as her's over there (and remember, Jean Treacy wasn't even that vital a witness), they are likely to be resentful, halting and unconvincing participants in the trial. It's a practice that should be stopped, therefore, before it catches on. Which would be a good outcome for the media, of course, even if it has still to make a convincing case of its own for getting its pictures.

Northern politicians really are a dreadful lot

The yobbish behaviour of politicians on all sides in Northern Ireland over the past few weeks means it is impossible to take any pleasure in the deal they all signed up to on Friday. They really are a dreadful bunch – the people of the North deserve any sympathy going to have such politicians in control of their destinies. Last Sunday's Channel 4 drama about Mo Mowlam was a timely reminder, therefore, of what a proper politician can achieve when she puts her mind to it. Julie Walters' stunning performance in the title role will win awards, and rightly so. What the drama really brought home, in its portrayal of the sulking David Trimble, a slightly cartoonish Martin McGuinness and a ridiculously self-important Gerry Adams, was that peace came to Northern Ireland in spite of its politicians, not because of them.