The Assembly, on the basis of an Alliance Party motion and a special standing order from the Northern Secretary, Mr Peter Mandelson, yesterday overturned the July resignation of Mr Seamus Mallon as Deputy First Minister.
The pro-Belfast Agreement parties in the Assembly, including the Ulster Unionist Party supported the Alliance motion re-confirming Mr Mallon as Deputy First Minister. The motion was carried by 71 votes to 28.
Anti-agreement parties deplored the decision. Mr Robert McCartney of the UK Unionist Party told the Assembly that it was an exercise in "political expediency" and a "disgrace" to the workings of the Assembly.
Shortly before the motion was discussed around 3 p.m. yesterday, Mr Mandelson introduced a standing order allowing the Assembly - by majority vote - to reject Mr Mallon's resignation, and re-affirm him in office.
Had this mechanism not been introduced a vote would have been required to re-elect both Mr Mallon and Mr David Trimble as Deputy First Minister and First Minister respectively.
This could have caused great difficulties for Mr Trimble as he needed 30 unionist votes to ensure his election.
With pro-agreement unionists in the Assembly numbering only 29 - 27 in the UUP, and two in the Progressive Unionist Party - Mr Trimble probably would not have been re-elected.
The presiding officer, Lord Alderdice, said he had received conflicting legal advice on whether Mr Mallon's resignation of July could be overturned.
The matter could be fully tested by judicial review but while he was in a position to take such a course he felt it was not appropriate for him to do so.
The DUP leader, the Rev Ian Paisley, said the decision to reconfirm Mr Mallon as Deputy First Minister represented an act of "amazing collusion" between the "motion and the Secretary of State".
"Here you have democracy stood on its head," he said.
Later, outside the Assembly chamber, Dr Paisley said the DUP would consider whether it should take legal action challenging the decision.
Mr Mallon said he resigned in July because he believed this was the only way of ensuring a meaningful review would be carried out leading to the implementation of the Belfast Agreement and the formation of an Executive.
He said the issue at stake was not about him personally but "about the working of the agreement".
Mr Mallon welcomed the passing of the Assembly motion, and said he regarded the vote as a reflection of cross-community support for his appointment.
Mr David Trimble, supported the motion on behalf of the Ulster Unionist Party.
"I want to see him back in the office and the sooner the better," he added.
Sinn Fein president Mr Gerry Adams, also supporting the motion, described the Mitchell review package breaking the logjam on devolution and decommissioning as "truly a watershed moment in our history".
Straying from the motion he added, "Despite the conditional and short-term response by the UUP at the weekend, the review's endorsement opens up the possibility of great change."
Mr Adams said the historic challenge facing the Executive in the days and weeks ahead would be to forge policies "from our differing attitudes on economic policy, on education, healthcare, youth training, equality matters and much more.
"That requires that we work together in co-operation and good faith.
"The difficulties within unionism will continue to cause problems in trying to develop a new political partnership."
Mr Adams said unionists had nothing to fear from sharing power with republicans. "Our future is bound up together," he added.
Mr Adams said that Sinn Fein's goal remained that of a united Ireland.
"We believe the Good Friday agreement is the transitional structure that will allow us to achieve that legitimate objective.
"Others in this Assembly will hold a different view. That's fair enough. But what we now have is the possibility that we can all pursue our political goals in partnership, as equals, in mutual respect and toleration," he added.
The Alliance leader Mr Sean Neeson said he proposed the motion re-affirming Mr Mallon in office because he believed this was the best way of seeing the Belfast Agreement implemented.
The will of the people as reflected in the referendum on the agreement last year was for this to happen.
"We want to give accountable democracy and overcome the democratic deficit," he added.
