Today's extraordinary Sinn Féin ardfheis has voted overwhelmingly in favour of a leadership motion expressing support for the Police Service of Northern Ireland.
Speaking moments after the vote was taken, party President Gerry Adams described the decision as "truly historic" and said the potential had been created to change the political landscape of the island "forever."
Sinn Féin President Gerry Adams votes at today's ardfheis
Delegates overwhelmingly backed party leader Gerry Adams and Martin McGuinness's call for the party to support the PSNI.
"Its significance will be how we use this decision to move our struggle forward," Mr Adams said.
Calling on the unionist community to respond positively to today's decision, he said there was a need for "an historic compromise" between the communities and for "a real dialogue - an anti-sectarian dialogue between nationalism, republicanism and unionism."
Mr Adams described the yes vote as "one of the most important decisions in the recent history of our country."
He told the ardfheis: "The decision we have reached is truly historic. We can use this decision to advance our struggle.
He added: "I am confirmed in my confidence that Sinn Féin has the talent, vision, determination and ability to build a new Ireland."
A lengthy six hour debate was dramatically cut short as the leadership forced a vote which will see the party move to take its place on policing bodies in Northern Ireland in the event of power-sharing returning.
Earlier, the Sinn Féin leader said support for the Police Service of Northern Ireland would move republicans into a new phase of their fight for a united Ireland.
Mr Adams told delegates Sinn Féin would remain united regardless of what opposition was expressed at today's meeting.
"The time is now right and I am appealing to you comrades to support this motion," he said. "Some of you may disagree. That is perfectly acceptable. "For example, Ógra (Sinn Féin's youth wing) disagrees with us on this issue.
"I wish they didn't but I respect their position and I especially commend their resolve to accept the outcome of this ard fheis (party conference) debate. "That is the way all of us need to face in today's discussions."
Mr Adams also said the Republic needed to catch up with the policing accountability mechanisms north of the border.
Mr Adams rounded on the SDLP, claiming it had failed to confront the issue of security force collusion with loyalist paramilitaries.
"My friends we cannot leave policing to the unionist parties or the SDLP or the Irish Government," he said. "We certainly cannot leave it to the British Government. "We cannot leave it to the securocrats. "So let's have our debate and let's take our decisions."
Moving the motion, Sinn Féin chief negotiator Martin McGuinness referred to last week's revelations of collusion within the RUC and urged delegates to deliver a resounding 'yes' to usher in a new phase of political success for the party.
Former IRA prisoner and Sinn Féin representative, Paul Butler said: "I have been interrogated and brutalised by the police. It is difficult for me to make a decision because of my personal experiences of policing." But supporting the motion, he added: "Those who want maximum change must be prepare to take maximum risks."
Activist Seán Oliver from north Belfast said that his local community knew all about bad policing. He claimed that the PSNI didn't properly investigate crimes against nationalists. He added that today's debate should mark the demise of the last of three pillars of unionism following the ending of the supremacy of the Orange Order and the one-party state in Northern Ireland .
Activist Seán MacBrádaigh said to loud applause: "A Republican searchlight must shine into the deepest, darkest recesses of the PSNI." Another delegate quoted the late republican Joe Cahill's famous words: "We have won the war, now let's win the peace."
