Brian Cowen has said that there was nothing wrong about his decision as minister for transport in the mid-1990s to grant a right of way to a business consortium which facilitated a development near Dublin airport.
He said the decision was based on an objective assessment and was not linked to associations one of the directors of the project had with Fianna Fáil.
Mr Cowen said his decision had to be viewed in the context of evolving industrial policy which saw a greater role for the private sector.
He told the tribunal that his thinking on the right of way had been influenced by a letter from his then Labour Party cabinet colleague Ruairí Quinn.
He said that Mr Quinn said the development planned by the business consortium known as Cargobridge fitted in with industrial policy based on the Culliton Report on job creation.
The tribunal is investigating contacts between Mr Cowen and lobbyist Frank Dunlop about the right of way.
Mr Cowen confirmed that he had not recalled the involvement of Mr Dunlop when initially approached by the tribunal.
He said that he had got other people to examine the department files on his behalf but that confidential letters sent to him by the lobbyist about the right of way were not in these records.
He said that as minister he had had dealings with Mr Dunlop who was advising the chairman of Aer Lingus, Bernie Cahill.
He also said that he knew the family of a director of Cargobridge, Michael McGuinness.
The father of Mr McGuinness was a councillor in Kilkenny and his brother, John McGuinness, is currently a Fianna Fáil TD.
Mr Cowen said that based on the facts collected about Cargobridge there were two storylines that could be constructed.
"One suggests that I did something arbitrary or untoward or with improper motivation to accord a benefit which was paid for by arbitration to a particular individual who happened to have a history of involvement with my party.
"Or you can look at the documentary evidence, the evidence of the secretary general of the department, of Mr Toomey [ the civil servant] dealing with the day-to-day issues, my own evidence and the opinion of Ruairí Quinn, Nora Owen and Pat Rabbitte when he was chairman of Dublin County Council and nearly all the councillors in relation to the rezoning.
"I would suggest that the facts accord with the latter scenario and not the former," he stated.
Mr Cowen confirmed that initially the department's position had been that a right of way would be conditional on rezoning and planning permission being secured.
He said that after receiving Mr Quinn's letter he had asked officials to reconsider the position.
He said that in the background there was movement politically, both domestically and in terms of the EU, which meant that semi-State companies could not regard the department as their "down town office" and would have to justify their positions.
He said that there was "a certain institutional arrogance" on the part of Aer Rianta in that it wanted the minister to object to developments near the airport without producing its own detailed development plans.
He confirmed that he showed Mr Dunlop a draft letter indicating that in principle he was prepared to grant the right of way. He also said that he gave Mr Dunlop copies of a letter on the issue which he had sent to Aer Rianta chief Noel Hanlon.
However, Mr Cowen said there was nothing untoward involved.
