The leader of the Seanad, Ms O'Rourke, told the House yesterday that a drafting error in the State Airports Bill made the legislation deficient and faulty.
This had borne out the concerns that she had voiced earlier about the measure, she said.
The Minister for Transport, Mr Brennan, strongly rejected claims that an error had been made.
Addressing an amendment tabled by Fine Gael, Ms O'Rourke referred to a report in The Irish Times on Tuesday that there was a mistake in a sub-section of the Bill relating to the pay and conditions of the person carrying out the duties of the chief executive of Aer Rianta.
She said she understood that a firm of solicitors had drafted the Bill at the request of the Minister and the Department.
Members of the House had a duty as legislators to scrutinise proposed legislation, she said.
If they knew that there was a drafting error, and the Minister did not want to go back to the Dáil to have it put it right, where did that leave the Seanad in the equation?
If there was an error, would it not be better for the Minister to ensure that the Bill was a proper one?
Mr Brennan stressed that the amendment was not necessary.
He said that the sub-section in question had been included during the debate in the Dáil, to address concerns that the Bill should provide that employees who continued to work at Dublin airport after the date for the vesting of assets in the new airport's authorities could not be subject to less beneficial terms and conditions except by way of collective agreement.
The section went on to state that in the case of anyone who was carrying out the duties of chief executive officer who was also an employee, the terms and conditions applicable before "the Dublin appointed day", must be determined in accordance with the relevant provisions contained in the 1998 Air Navigation and Transport Amendment Act.
Moving his party's amendment, Mr Fergal Browne (FG) said that according to legal advice obtained by Fine Gael, the Bill was fundamentally flawed.
The Minister responded that the reference in the Bill to the 1998 Act was correct, as it referred to the position before the Dublin appointed day.
The new text applied only after that date.
Mr Brian Hayes (FG leader in the House) said that the issue at stake was not of itself huge. But he did not see why the Minister had a difficulty in amending it.
He wondered if Mr Brennan's reluctance had something to do with the need to have the Bill referred back to the Dáil.
They had a duty in the Seanad to ensure that the Bills it passed were accurate.
The explanation that had been given by Minister Brennan was not "on the ball".
The amendment was defeated by 28 votes to 14. Ms O'Rourke voted with the Government.