The Supreme Court has reserved its decision on whether it should declare the Dáil's Public Accounts Committee acted unlawfully in relation to former Rehab Group Chief Executive Angela Kerins.

Lawyers for Ms Kerins told the Supreme Court that the Dáil's Public Accounts Committee devised a process to seek private information that was outside its remit.

They are asking the court to declare the committee's actions in 2014, in relation to Ms Kerins, unlawful.

Earlier this year, the court found it had the power to declare the actions of the PAC unlawful if it found the committee "as a whole" - not just individual members - acted outside its remit and breached the terms of the invitation it extended to Ms Kerins to appear before it.

Both sides gave submissions at today's hearing.

Lawyers for the State have said the court has already decided the committee acted outside its powers and should not go any further.

Senior Counsel for Ms Kerins, John Rogers, told the court the invitation issued to Ms Kerins to appear was issued on limited terms, but other entirely private matters were pursued at the PAC's hearing on 27 February 2014.

He claimed this was done consciously by the committee.

He said the committee, acting collectively, had devised a process where the private affairs of Ms Kerins and the Rehab Group were to be pursued with the purpose of seeking private information outside its remit.

Mr Rogers said what happened to Ms Kerins had not been remedied in any way by the Oireachtas.

There had been no acknowledgement that the processes pursued by the PAC was wrong, except in the Supreme Court's judgment.

Mr Rogers said the Public Accounts Committee had an expansive view of its role and saw itself as being a challenge to the methodologies of bodies in the charity sector, delivering services to disabled people.

But the breadth of the agenda it had was not outlined in the letter to Ms Kerins on 18 February 2014, inviting her to appear before it.

Mr Rogers said the meeting was controversial from the start, as Ms Kerins was quizzed about her lawyers contacting the committee the previous day looking for clarity on what she was to be asked about.

He said Ms Kerins was treated to commentary about her private communications with people completely unrelated to rehab. 

Mr Rogers said there was a critique of Ms Kerins' salary and an intervention into the private affairs of private company.

He said she was asked about her car and asked about the salaries of others working for Rehab.

Mr Rogers said what happened was an outrage and the chairman had not done his job.

The court heard Ms Kerins was hospitalised from 2 March to 11 March 2014 and resigned from the Rehab Group on 2 April. She claimed the 27 February meeting and a later meeting in April amounted to a witch-hunt against her. 

Mr Rogers said a member of the committee, Shane Ross, had described Ms Kerins' resignation as an achievement.

In its judgment in February this year, the Supreme Court found there was no "absolute barrier" to the bringing of proceedings concerning the actions of an Oireachtas committee.

The court found it had the power to declare PAC's actions unlawful in the light of the fact that the committee was acting outside its remit and that a relevant Dáil committee had come to the same view.

Senior Counsel for the Dáil, Paul Gallagher, said the court should not make the declaration that the committee acted unlawfully. 

He said the finding that PAC acted beyond its remit was significant and fully accepted. He said the court should go no further.

Mr Gallagher said a declaration by the Court that the Committee had acted unlawfully would have a chilling impact on how the Oireachtas conducts its business and on the freedom of parliamentary expression.

He said there was an understanding that there would be questions at the hearing on salaries and on corporate governance generally. It was of great concern to the PAC how money was being spent and if value was being received for it.

He said that was the basis of the invitation to Ms Kerins and was her own understanding of it. He said the issue was whether the invitation was significantly deviated from and to examine that the court had to look at the hearing as a whole. Mr Gallagher said the court could not analyse the individual utterances of members of the committee and could not analyse their tone, content or motivation.