The threshold for a united Ireland must be a majority of the people in Northern Ireland voting for it rather than unionists consenting to unification, according to the SDLP.
The SDLP in its unity document, A Better Way to a Better Ireland, published yesterday in Belfast, Dublin and Newry, urged the creation of a united Ireland based on the principles and protections of the Belfast Agreement.
The key proposals in the document are that in a united Ireland the Assembly would remain as a regional parliament of a united Ireland rather than of the United Kingdom, that the Northern Executive would continue, and that the equality and human rights provisions of the agreement would be maintained.
People in Northern Ireland could still identify themselves as British or Irish or both and hold Irish or British passports. TDs from the North would be elected to the Dáil to represent Northern Ireland constituencies.
And while MPs would no longer be returned from Northern Ireland to the House of Commons, Northern politicians, if they wished, could be represented in the House of Lords, just as Northern Irish representation is permitted in the Seanad.
A high level of British-Irish co-operation would be maintained.
"In particular, just as the Irish Government has a say in the North now, the British government would have a say in the North in a united Ireland," the paper states.
A united Ireland could only come about by a majority of people in the North backing unification in a Northern referendum which should take place "once the agreement's institutions have bedded down and are operating stably".
A Northern result in favour of unification would have to be backed by a similar outcome in a referendum in the Republic, according to the SDLP proposals.
The SDLP states that "uniquely" among Northern parties it favours a united Ireland if a simple majority in the North votes for it.
"The SDLP recognises that it would be wrong to force Northern Ireland into a United Ireland without the consent of a majority. We are equally opposed to any suggestion that Northern Ireland should be kept in the United Kingdom despite the vote of a majority," according to the unity document.
"We cannot agree with Sinn Féin president Gerry Adams that unionist 'consent and assent' would be required to bring about a united Ireland. Nor can we agree with Jeffrey Donaldson and other unionist politicians who have advocated the same position. The threshold for a United Ireland cannot be any higher than for a United Kingdom.
"We are emphatic that unity must not be about the entrapment of a new minority," it says.
The document says that the Belfast Agreement enjoyed more support than either the continuation of the United Kingdom or a United Ireland.
"It is a democratic common denominator between nationalists and unionists. It would be perverse for the agreement not to endure in a united Ireland," it adds.
"It is also right in practice. Those who rely on demographic change alone must realise that it will not deliver unity any time soon. Nor will it deliver stability.Census politics will never do away with the need for consensus institutions of government.
"Voters in the southern referendum will also want to be assured that a united Ireland will not bring instability or uncertainty. They will not want to see the Good Friday agreement undone."
The paper says unity would require changes to the Irish Constitution to ensure it offered an "inclusive home" for everyone.
The SDLP also said it was the party of "true republicanism" and the only party that could achieve a united Ireland.
The unity document describes the agreement as "a covenant of honour between nationalists and unionists that should endure".
SDLP leader Mark Durkan, at the launch of the paper in Belfast Castle yesterday, said: "As true republicans, we strive to protect - not disgrace - the ideal of the United Irishmen that all people are equal, 'Catholic, Protestant and Dissenter'.
"We stand by the 1916 Proclamation's commitment to 'cherish all the children of the nation equally'. We don't rob children of their fathers. We don't deny child poverty the priority it needs or child services the support they deserve.
"We stand for justice - not in the way of justice. We respect the will of the people. That is why we are 100 per cent for the Good Friday agreement, just as we are 100 per cent for a united Ireland."
