Former communications minister Michael Lowry claims he has been discriminated against in a decision to deny him the bulk of his legal costs for the Moriarty Tribunal.
The High Court today granted Mr Lowry permission to bring judicial review proceedings over the tribunal's decision last October to award him just one-third of his costs.
The costs are expected to run into many millions of euro.
The tribunal was set up in 1997 to investigate alleged payments to Mr Lowry and to the late taoiseach Charles Haughey.
The tribunal decided to grant just one-third of costs to Mr Lowry because of his failure to cooperate fully.
He claims that he is being discriminated against in comparison to Haughey and to businessman Ben Dunne, a tribunal witness, who were awarded their full costs.
The application for judicial review was made by Niamh Hyland SC, for Mr Lowry, before Mr Justice Michael Peart.
It will come before the court again in March.
Mr Lowry wants a declaration that Mr Justice Michael Moriarty acted unreasonably and/or disproportionately in withholding two-thirds of his costs.
It is claimed the tribunal erred in making findings of alleged failure to co-operate, or the giving of misleading information to it, without adequate evidence to support that conclusion and without meeting the tribunal's own rules in relation to standard of proof.
It also erred in making such findings without affording him a right to a fair hearing, it is claimed.
He wants the court to order that he should be entitled to his full costs.
In his action, Mr Lowry says the tribunal sat in public a total of 384 days, 240 of which were concerned with matters relating to the former Fine Gael minister and which were divided into "the money trail" module and the "GSM (mobile phone) licence" module.
The only findings of non-cooperation and concealment against Mr Lowry, who is a TD for Tipperary North, were in relation to the money trail module, it is claimed.
There were substantial parts of the 654-page report on the money trail that do not concern Mr Lowry or assert non-cooperation by him, it is argued.
It is claimed that 70% of the tribunal's time, resulting in a 1,696-page report in two volumes, was taken up with the mobile phone licence module and no finding of non-cooperation was ever advanced or made in relation to his conduct in relation to this.
Mr Lowry, it is claimed, cooperated extensively with the tribunal not just during the public sitting days but at numerous private meetings with the tribunal's legal team.
Although Michael Kelly, the solicitor who represented him during the tribunal, died in March 2011, his new lawyers have drawn up a draft working estimate of more than 9,000 hours (excluding senior and junior counsel's time) worked in representing him.
He is also currently facing a separate legal action for alleged non-payment of around €1m in outstanding fees claimed by his accountant for work related to the tribunal.
Ms Hyland said that while the tribunal concluded Mr Lowry had been involved in falsifying and suppressing documents to mislead it (tribunal) as to the true nature of his involvement in transactions that were being investigated, it had not met its own standard of "beyond any doubt" in relation to a test for an adverse costs finding.
Mr Lowry was the only party that has had his costs withheld on the basis of non-cooperation, Mr Hyland said.