Mr Gormley's claim is being resisted on the grounds of fair comment, qualified privilege and a further defence of justification.

BBC: Sinn Fein legal bid to stop libel action by Declan Gormley

Mr Rusbridger had said media laws were "doubly menacing" when applied to reporting of proceedings of Parliament - usually covered by qualified privilege.

BBC: Parliamentary question gag lifted

So mentions like John Hemming's are protected by absolute privilege as far as MPs are concerned, under Article 9 of the Bill of Rights, and by the normal "qualified privilege" as far as journalists are concerned.

BBC: Parliamentary privilege, MPs and super-injunctions

In July, a leading British book publisher warned of the 'chilling effect' the law would have on journalism, after a judge rejected its defence of qualified privilege in a libel action brought by a former police officer.

BBC: NEWS | UK | Landmark decision for 'free speech'

More public events would be covered by "qualified privilege", so that a fair and accurate report of them would be protected from defamation actions - so the protection applied to reporting what is said at local council meetings, would be applied to, for example, the proceedings of scientific conferences.

BBC: Cheering the changes

Now five international media organisations have supported his stand, urging the tribunal "to recognize a qualified privilege for journalists not to be compelled to testify about their news gathering before this court unless certain conditions are met - namely that the information is absolutely essential to the case and that it cannot be obtained by any other means".

BBC: Milosevic tribunal calls BBC witness