Renua leader Lucinda Creighton says she thinks a legal action by Denis O'Brien against a Dáil Committee is "unwise".
Mr O'Brien is taking a case against all 10 members of the Committee on Procedures and Privileges.
It's after the CPP rejected his complaint that Deputy Catherine Murphy abused parliamentary privilege when making claims about his banking arrangements with IBRC.
Deputy Creighton says it's essential to defend the integrity of the Houses of the Oireachtas.
"I think this is very unwise, it's ill-judged and it's very misfortunate that Mr O'Brien has chosen to go down this road," said Deputy Creighton.
"I totally support and fully stand by the members of the committee and indeed by the right of Deputy Murphy to speak on the record in the Dáil on issues that are of huge public concern, and we will continue to maintain that position, and to support the right of members of the Oireachtas to speak without fear on the floor of the Dáil."