The Northern Ireland Assembly has voted to devolve policing and justice powers from London.
Three of the main parties - Sinn Féin, the DUP and the SDLP - had been backing the proposal.
The Ulster Unionists were opposing the move.
This evening's vote paves the way for full devolution from next month.
The Assembly decision followed an acrimonious debate in which the Ulster Unionists resisted pressure to support the move, which will now lead to the creation of a Department of Justice for Northern Ireland after the powers are devolved by April 12.
Out of the 105 votes cast, a total of 88 were in support of the move, with only the UUP voting against.
Democratic Unionist leader and Northern Ireland First Minister Peter Robinson attacked the UUP decision to vote against the devolution plans.
He said the party was seeking political advantage and added: “I believe it is time for us all to move forward. There must be no going back to the bad old days of the past.
“Throughout history there are times of challenge and defining moments. This is such a time. This is such a moment.”
Mr Robinson added: “Leadership is not about what’s easiest, or what best suits our party interests, it is about doing what is right for our people.”
The UUP claimed the ministerial Executive must sort out other outstanding matters – such as the longstanding row over post-primary school transfer arrangements – before it can take on law and order functions.
Its leader Reg Empey said: “I am immensely proud of the sacrifices my party has made for the cause of peace. Our determination to make Stormont work for all the people of Northern Ireland – unionists, nationalists, all of us - continues.
“Our whole-hearted support for the brave men and women of the PSNI continues unabated.”
Mr Empey added: “As a democratic political party pledged to making power-sharing work in an inclusive manner for all the people of Northern Ireland - and we exercise our rights refusing to bow to the blackmail and bullying to which we have been subjected in recent weeks.”
Deputy First Minister Martin McGuinness questioned the logic of the UUP stance.
“The UUP are on record as stating that they will not support the election of a local minister to oversee the administration of policing and justice until there is agreement to test 10 and 11-year-old children to determine which school they will attend,” he said.
“I have to say that these are the most dysfunctional political positions I have ever come across.”
He added: “The Hillsborough Agreement provided an opportunity for a new start... I acknowledge that this is a challenge to us all but it is one to which we all must rise.”