The High Court has refused to grant an order to businessman Denis O'Brien directing PR company Red Flag to reveal the identity of a client, who commissioned a dossier about Mr O'Brien.
Mr O'Brien claims the company, its Chief Executive, Karl Brophy, Chairman, Gavin O'Reilly and other members of staff have been involved in a conspiracy to damage his interests.
He claims parts of the dossier were defamatory.
Mr Justice Colm Mac Eochaidh ruled this afternoon that the law required Mr O'Brien to establish a very high degree of wrongdoing on the part of the person he wanted to identify.
But he found that Mr O'Brien had not proved that the dossier had been published anywhere and without publication there could be no defamation.
He also found that Mr O'Brien had not proved that harm had been done to him.
He also found that Mr O'Brien had not proved that the motivation of the unnamed person was to do harm to him.
Mr Justice Mac Eochaidh also said that Mr O'Brien's lawyers had argued that the duty of confidentiality owed by Red Flag to its clients should be outweighed by the interest in obtaining evidence of wrongdoing.
The judge said Mr O'Brien knew full well how important confidentiality was.
He said Mr O'Brien had taken a case in 2013 against the Sunday Times in which he argued that irreversible harm would be caused to him if certain financial details were published.
The judge said Mr O'Brien would have had to have had a very strong case indeed, almost to the point of certainty, that wrongdoing had been committed against him, if he wanted the court to make orders that would have caused irreversible damage to the defendants.
Lawyers for Red Flag said they would be seeking their costs.
A full hearing of Mr O'Brien's case against Red Flag has yet to take place, but Mr Justice Mac Eochaidh said there was no urgency to the case.
He said if the people alleged to be conspiring against Mr O'Brien were as untrustworthy as he alleged then any evidence of wrong doing would have been destroyed by now.
Also he said the existence of this case would have a "quietening" effect on any conspirators.
The case will be back in court again next month.
