Counsel for former senator Don Lydon has said that the actions of a "rather gullible tribunal" resulted in lobbyist Frank Dunlop being able to devise a "road map" that the tribunal then followed.
Séamus Ó Tuathail SC criticised the way in which Mr Dunlop had been provided with details of council votes and meetings by the tribunal in 2000 to help him recall information about the various developments in which he had been involved.
He said it meant Mr Dunlop never had to rely on his memory.
He said the documents were provided by a "rather gullible tribunal" and Mr Dunlop became the architect of the modular system adopted by the tribunal.
"That is not the way that I would deal with it when I have finalised my book on the matter," Mr Dunlop responded.
He said that in an effort to ensure the tribunal did not become "systemically dysfunctional", he had suggested a road map should be devised and he would give information about every development he was involved in.
"You could pick off your enemies as you wished, it was shooting fish in a barrel after that," Mr Ó Tuathail said.
Mr Dunlop said he paid Mr Lydon £1,000 for his support of the Quarryvale development "within days" of a crucial vote on the project in May 1991. The handover happened in the car park of the Dublin County Council building on O'Connell Street, Mr Dunlop said, and Mr Lydon had asked for the money.
Mr Lydon has acknowledged he got an unsolicited political donation of £1,000 from Mr Dunlop, the tribunal heard, but denied it was connected to his support of the project.
Mr Ó Tuathail pointed out that Mr Lydon did not vote for the project in May 1991 because he was not present for the meeting. He said Mr Lydon would deny that he was particularly supportive of the project.
David Burke, counsel for the estate of the late Tom Hand, asked Mr Dunlop about various unexplained financial transactions in Mr Dunlop's accounts, which he said amounted to £3.56 million.
He went through his calculations in detail, adding up the sums as he proceeded, prompting Mr Dunlop to respond: "I'm delighted you're a barrister and not working for the Revenue Commissioners."
He added: "For a moment there I thought you were going to convert it to dollars," when Mr Burke came up with another figure. Mr Dunlop denied that he paid a senior politician £25,000 at a meeting in Powers Hotel, Kildare Street, Dublin in September 1993.
