Businessman Denis O’Brien will give evidence on Thursday in his High Court action against a Dáil committee.

He alleges two TDs “clearly disregarded” the constitutional separation of powers between parliament and the courts, when they made statements in the Dáil about his banking affairs.

Mr O’Brien maintains the Dáil committee failed to “properly police” Social Democrats TD Catherine Murphy and Sinn Féin TD Pearse Doherty, in relation to their statements, and the court should find those amounted to “unwarranted interference” with the judicial domain.

The TDs knew, when making their statements in May and June 2015, that Mr O’Brien had initiated proceedings to prevent RTÉ publishing details of his banking affairs with State-owned Irish Bank Resolution Corporation, his counsel Michael Cush SC argued.

Mr O’Brien’s lawyers had formally complained at the time that the statements were a “gross abuse” of Dáil privilege and breached the sub judice rule, he said.

The outcome of the case, expected to finish next week, will rest on Ms Justice Úna Ní Raifeartaigh’s interpretation of various articles of the Constitution.

The action is against the Dáil Committee on Procedure and Privileges (CPP) and the State, who are relying on legal submissions and not calling any witnesses.

Court No 29 in the Four Courts, a small courtroom, is expected to be packed for Mr O’Brien’s evidence.

He is the sole witness being called by his side, after the High Court previously ruled he could not call an American constitutional law expert.

The judge told Mr Cush on Wednesday he could call Mr O’Brien either at 11am or after counsel finishes his submissions later on Thursday.

‘Clear disregard’

In arguments on Wednesday, Mr Cush said the courts can intervene when there is “clear disregard” by members of the Oireachtas of the separation of powers.

This was one of the “extremely rare” cases when there was such a clear disregard, he said.

Deputy Murphy made statements in the Dáil on May 6th, 2015, after Mr O’Brien initiated his case and she put further information into the public domain after he got an injunction against RTÉ on May 21st, restraining publication of his banking affairs, counsel said.

It was his case she was certainly aware of that injunction as she issued statements and tweets expressing concern about the extent of it and the implications for freedom of the press.

She also referred to having “rattled a few cages” as a result of her statements and had said she did not regret that, he said.

Because of a “so-called constitutional crisis” concerning what the media could report as a result of that injunction, it was “absolutely certain” Mr Doherty must have been aware of the injunction when he made his “highly detailed” statement on June 9th, Mr Cush said.

Article 15.13 – the constitutional provision stating TDs are not “amenable” to the courts for utterances made in the Oireachtas – was among various provisions relied on by the defendants in opposing Mr O’Brien’s case, he said.

Article 15.13 conferred an “enormous privilege and immunity” on an individual member, that privilege must be asserted by them and must be “strictly construed”.

Various court decisions on Article 15.13 should be read in the context of the concepts of punishing or disciplining TDs and did not mean TDs’ actions cannot be questioned, he argued.

Unwarranted interference

Because Mr O’Brien had not sued the TDs and was not seeking any relief against them, this case was different, he argued.

What was sought were declarations their statements amounted to unwarranted interference in the judicial domain and, in that context, Article 15.13 was “not relevant”.

Counsel also argued Mr O’Brien had a right to a proper hearing and determination of his formal complaints to the CPP about the TDs’ statements.

The complaint against Ms Murphy alleged a “gross breach” of Dáil privilege but the CPP did not address those claims, he said.

It had applied the wrong test and did not address whether the TD had discharged the onus to avoid prejudicing the outcome of legal proceedings.

The committee’s response to the complaint about Mr Doherty involved an incorrect interpretation of Dáil Standing Orders, he also argued.