The Fine Gael leader in the Seanad, Mr Maurice Manning, told Judge John O'Hagan that, short of treason, he could not think of a worse charge that could be levelled against the Taoiseach than bribery or corruption.
Called by Mr Rory Brady SC, counsel for Mr Ahern, to give evidence as to the possible effects allegations of corruption might have on a politician, he said the consequences would be "monstrous".
Mr Manning said he remembered the Sunday Business Post article well and recalled trying to eliminate who it might be. He had come to the conclusion early on that it referred to Mr Ahern.
He told Mr Brady that if such charges had been proven correct, the Taoiseach would have had to resign and his Government would break up.
"He would never hold ministerial office again, lose his party whip and have to fight any future election as an Independent," Mr Manning said. In the media and elsewhere he would be referred to as the disgraced former Taoiseach.
His credibility would be gone for ever.
He said significant damage had been done to Mr Ahern, certainly in the short term, as a Sunday Independent opinion poll had revealed a week later. Even though he had publicly denied the allegations, the poll showed more than half surveyed had not believed him.
Cross-examined by Mr Brendan Grehan, for Mr O'Brien, he said the fact that people had not believed him must have been hurtful to the Taoiseach.
When Mr Grehan suggested that Mr Ahern remained the people's choice as Taoiseach in other opinion polls and could not have been too severely damaged in his reputation, Mr Manning replied to the accompaniment of loud laughter: "He has lost the last six by-elections."
Ms Sinead McSweeney, a special adviser in the office of the Attorney General, said she quickly associated Mr Ahern with the senior politician referred to in the Sunday Business Post article.
"It referred to a senior Fianna Fail politician who had been in politics in 1989 and was still in politics and that a general election was inevitable.
"On that basis it could only have referred to the Taoiseach. If it had been a senior minister that person could resign.
"It wouldn't have caused difficulties within the coalition for the Government, but if it was the Taoiseach, that wouldn't have been an option. A senior minister had earlier resigned and there hadn't been an election."
Mr Nick Reddy of the Government Press Office said journalists who rang up had already drawn the conclusion it was the Taoiseach on the basis that, of the 1989 government, only four members of that administration were in the current administration and only two of them were at senior level.