The Government has received legal advice that measures to prevent the re-flagging of ships could be unconstitutional.
Taoiseach Bertie Ahern told the Dáil that "I am advised it would be extremely difficult to deal with the issue of re-flagging in both Irish law and international law".
However he told Labour leader Pat Rabbitte that he would look at his party's Bill which Mr Rabbitte said "addresses the question of whether a link exists between a flagship and the state in which it is registered and enables the Minister to prohibit a vessel being registered in a state to which no connection exists".
The Taoiseach said he could not introduce legislation when he had advice that it could be unconstitutional, but the Attorney General was closely examining the matter. The legal advice was that "we would not be able to legislate on flagships as it would be contrary to matters that are set out in Bunreacht na hÉireann".
Mr Rabbitte raised the issue in the wake of the Ictu move to defer a decision on joining talks for a new social partnership agreement.
Mr Rabbitte said Ictu's verdict showed the wide concern about the operation of social partnership, the handling of the dispute at An Post and the decision of Irish Ferries to dismiss its entire workforce and to employ people at reportedly less than half the national minimum wage.
"It is the issue of displacement, more than any other, and its implications throughout the economy that has caused the breakdown of talks," he said.
Mr Rabbitte claimed that while the Taoiseach had roundly condemned the Irish Ferries decision, neither he nor any of his ministers had said since what they intended to do about it.
"His letter to the leader of Siptu has completely failed to address the issue." He called for the Government to look at Labour's Bill, which "seeks to build on the United Nations Convention on the Law of the Sea".
Such a measure "would enable the Minister to prevent a ship being registered in any country that can be thought of off the top of one's head with no connection of any kind between that state and the origins of the vessel".
Mr Rabbitte warned that "if the issue of displacement is not addressed, with the consequent knock-on effect it could have in other areas of the economy, it is highly unlikely a new social contract would be agreed, with all the implications that would have.
"In the absence of any political will to do anything, the Taoiseach can easily get legal advice suggesting it might not be possible for one reason or another."
He said the issue was "wider than the issue of Irish Ferries".
Mr Ahern said a commitment had already been given to Siptu and Ictu on improving existing legislation. The Government would share its legal advice with the unions. Mr Rabbitte "knows I cannot introduce legislation when I have advice that it would be unconstitutional", but he would look at the Labour Bill.
