Denis O’Brien has lost his legal action over statements made about his banking affairs with the IBRC on the floor of the Dáil.
The businessman claimed the statements effectively decided a case he was taking against RTÉ and therefore strayed into the work of the courts.
The deputies argued their comments were protected by Dáil privilege and the High Court has agreed.
Mr O'Brien was not in court for this morning’s judgement.
In a statement this afternoon, Denis O'Brien has said he is disappointed by today's judgment and intends to study it in detail before deciding whether to appeal.
However he said he was encouraged by several sections of the adjudication by Ms Justice Úna Ní Raifeartaig.
In particular the businessman highlighted where the judge said this case may throw light on the need for a general examination of the area of parliamentary privilege, particularly when Dáil deputies are discussing matters before the courts.