Ireland's low corporate tax rates, a key factor in attracting foreign investment, are threatened by the Nice Treaty, according to the anti-Nice campaigner, Mr Anthony Coughlan, of the National Platform.
Nice removed the Irish veto on harmonising taxes in the single currency zone, he said. "Articles 1.11 and 2.1 of the Treaty of Nice remove the veto we have at present on harmonising company taxes in the euro-zone, thereby abolishing the principal incentive we have for keeping foreign capital in Ireland and attracting new foreign investment here.
"At present Ireland can veto any such EU development, but under these provisions of Nice for so-called 'enhanced co-operation', eight or more EU states can harmonise taxes among themselves, even if the others disagree.
"British politicians have called Ireland a tax haven, like the Cayman Islands. Germany, with its high tax rates, wants a level playing-field for company taxes in the euro-zone and wants Ireland to raise its low 12.5 per cent tax rate to remove the incentive for German and other companies to move here."
He said Articles 2.13 and 2.14 of Nice removed the veto Ireland now had on the rules of the structural funds.
"What we contribute in the future will effectively be decided by a qualified majority vote on the EU Council of Ministers, a body on which Ireland will have seven votes out of 345 in an enlarged EU of 27 states," he said.
The Sinn Féin TD, Mr Caoimhghín Ó Caoláin, told a party conference at the weekend that the Government had "defied democracy" after the last referendum.
"When the people voted against the Treaty of Nice, the Government refused to implement their decision," he said.
"Worse than that, they openly defied it. Within days of the vote, the Taoiseach and the Minister for Foreign Affairs told the other EU governments to proceed with ratification of Nice despite the rejection of the treaty by this State."