Ivor Callely is to ask the High Court today for leave to challenge the Seanad Committee that suspended him over his expenses claims.
The Select Committee on Members' Interests, who are investigating the controversy, made a number of findings against the Senator who quit Fianna Fáil last month.
The Senator is going to the High Court apparently with the aim of securing a legal review of decisions made by the Seanad Committee that suspended him without pay for 20 days.
The committee investigating his expenses found that he misrepresented where he was residing to claim allowances amounting to more than €81,000.
Mr Callely who rejects the finding is also facing an investigation over his mobile phone expenses.
Yesterday, his lawyers made a brief appearance in the High Court to submit a lengthy affidavit to Mr Justice Sean Ryan so that he could read the papers before today's hearing.