Ardfheis debate:Ardfheis delegates voted by a margin in excess of 10-1 to change policing policy after more than six hours of debate.
Party president Gerry Adams hailed the result which was greeted with a spontaneous standing ovation and sustained cheering. "This ardfheis acted in the national interest," he said.
Turning to the anticipated response from DUP leader Ian Paisley and the British government, he added: "We look to others to do the same in the time ahead."
Urging republicans to be cautious in the days ahead, Mr Adams said: "As others consider the decision taken today let's take it very easy, very calmly."
To enthusiastic applause he added: "You have created the opportunity for a significant advance in our struggle. I see the leadership of this party on the floor of this hall in front of me."
Republicans and unionist had now to reach an historic compromise.
The motion "commits fully" to support for the PSNI and the criminal justice system, and to take up places on the Policing Board and the District Policing Partnership Boards.
However, it is qualified because the party's ardchomhairle has been mandated to implement it only if power-sharing is established and when satisfactory arrangements to transfer policing and justice powers are agreed - or failing that to support the PSNI when new British-Irish "partnership arrangements" are in place.
The debate was unexpectedly called to a conclusion at about 5.30pm when delegate Frank O'Neill unexpectedly called for a vote to be taken. A simple majority of the 982 voting delegates was needed to force a vote but it was passed by acclaim.
Pearse Doherty, who chaired proceedings at that point, then outlined the series of 10 amendments which still stood at that point. Eighteen had been tabled with the remainder withdrawn during the course of the debate.
Delegates including those on the ardchomhairle, voted to support just five amendments and none of these substantially altered the original leadership position.
The first amendment to be passed demanded the specific abolition of plastic bullets, while the second successful amendment stressed that changes to policing legislation had been secured by Sinn Féin.
The third successful amendment changed the wording of the original ardchomhairle motion to include a call for an end to "repressive policing and any form of criminalisation of republicanism".
Delegates also backed an amendment modifying slightly a denunciation of policing practices to date in Northern Ireland.
The final successful amendment changed the introduction of the motion, altering it to specify Sinn Féin's specific commitment to the "establishment of a 32-county democratic republic".
The now-amended main motion was opposed by only a handful of delegates. Those against included many speakers from Sinn Féin's youth body, who were mandated to vote against the motion. All told they had about 35 votes. Some other cumann were also mandated to vote against the motion, which would indicate that about 10 per cent of the 982 voting delegates would vote No. However when the vote was called, it was clear that substantially fewer than 100 delegates had voted against.
Opponents who spoke got vocal support from the floor, but this was not fully translated into voting support. The announcement of the result was followed by a standing ovation and cheers. There was no sign of a walkout nor any indication of dissent.