The former Fianna Fáil minister Mr Ray Burke is facing €10 million in legal fees after the chairman of the planning tribunal rejected his application for the State to pay his costs.
Mr Burke had been found by the previous chairman of the tribunal, Mr Justice Feargus Flood, of having received a number of corrupt payments and of being obstructive to the inquiry.
Yesterday, his successor as chairman, Judge Alan Mahon, said Mr Burke was a crucial witness who had set out to deliberately mislead the tribunal in the hope and expectation that the inquiry would prove inconclusive or would produce erroneous findings.
The judge said Mr Burke's non co-operation - while impossible to measure in absolute terms - was of such a magnitude that it fundamentally challenged the very purpose of the creation of the tribunal.
He said it was abundantly clear "that Mr Burke decided from an early stage not to co-operate with the tribunal and that this approach and stance was maintained by him throughout the inquiry".
"It is clear that the failure on the part of Mr Burke to co-operate with and give truthful evidence and information to the tribunal was of such a degree and such an extent as to cast a shadow over all of the evidence which directly related to the issues being investigated by the tribunal."
Judge Mahon said that when Mr Burke did appear to co-operate with the tribunal such co-operation was only superficial and given to the extent necessary to create the impression of co-operation.
Judge Mahon indicated that it was Mr Burke's failure to co-operate with the inquiry rather than the finding of corruption made against him that had been central to the tribunal's decision not to award him his costs.
"I am quite certain that, had Mr Burke largely co-operated with and given truthful evidence to the tribunal, I would be favourably disposed to awarding him at least a portion of his costs, even in the face of the very serious substantive findings of corruption," the judge said.
Judge Mahon said Mr Burke's lack of co-operation prolonged the work of the tribunal. However there was no indication in yesterday's ruling that the tribunal sought to have the former minister pay some of the inquiry's own costs.
Counsel for Mr Burke had previously argued that the former minister should receive his costs as he had not been specifically warned by the tribunal that his evidence was false.
However this argument was rejected as "without merit" by Judge Mahon.
Mr Burke last September initiated a legal challenge to Judge Mahon - who had not heard some of the evidence himself - dealing with the issue of costs.