The DUP will appeal the High Court's rejection of its legal challenge to the election of Mr David Trimble and Mr Mark Durkan as First and Deputy First Ministers.
The party's deputy leader, Mr Peter Robinson, described the judgment as "somewhat perverse". He said: "Over the next few days, we shall be studying the judgment in more detail before launching an appeal to the Court of Appeal in Northern Ireland. "Indeed, it may well be the case that this matter will ultimately have to go before the House of Lords before being finally determined."
The North's Arts Minister, Mr Michael McGimpsey, said it was now time for the DUP to work constructively with Ulster Unionist ministers at Stormont.
"The DUP's High Court defeat is no surprise," said Mr McGimpsey. "The judgment clearly underlines the legitimacy of the government's decision to set the next date for elections in 2003 and the vote for the First Minister.
"The only reason the DUP wish to appeal the decision is to use it as a vehicle for cheap publicity in the new year. The time has long since passed for this sham-fight opposition to the Agreement to stop."
Mr McGimpsey said everyone knew the DUP was anti-agreement in name only. "They sit on every Stormont Assembly committee with Sinn FΘin - there have been over 2,000 meetings. They sit on the Assembly Commission with Sinn FΘin, administering a multi-million pound budget.
The DUP also sat on the new Policing Board unconditionally, he said. "If Sinn FΘin joined the board, they would not leave. The DUP and Peter Robinson need to catch themselves on. Think of the benefits for unionism if UUP and DUP ministers worked together in Executive Committee meetings," Mr McGimpsey added.
The High Court decision was also welcomed by the Northern Secretary, Dr John Reid.
"I have always believed that the government acted entirely properly and today's judgment vindicates that assessment," he said.
"What really matters is that everyone in the Assembly and the Executive makes full use of the period of stability we now have to deal with the economic and social issues that face Northern Ireland.
"The people of Northern Ireland have shown that they value devolved government.
"I have every confidence that under David Trimble and Mark Durkan's leadership the Executive and the Assembly will grow in strength and continue to deliver for the people of Northern Ireland."
The Alliance leader, Mr David Ford, said the High Court decision would be welcomed by "all those who wish to see stability and progress in Northern Ireland".