Nick Barber’s post on a Scottish referendum raises many interesting issues, not least the implications of setting the issue in the context of British constitutional development as a whole. He misses at least two pieces of the jigsaw, however, which need to be factored in if a more comprehensive view is to be taken.

The first issue is the experience in Northern Ireland of such referenda. In March 1973 a referendum was held as to whether Northern Ireland should remain part of the United Kingdom and whether it should join with the Republic of Ireland to form a united Ireland. Nationalists boycotted the poll and the result was an overwhelming vote in favour of the Union. Since then, the possibility of a repeat referendum has been one of the elements of the Peace Process.

The current provisions are set out in the Northern Ireland Act 1998. This partially implemented the Belfast Agreement, and provides for a referendum on independence for Northern Ireland in certain circumstances. Section 1 provides that “Northern Ireland in its entirety remains part of the United Kingdom”. In rather convoluted drafting, the section further provides that Northern Ireland “shall not cease to be [part of the United Kingdom] without the consent of a majority of the people of Northern Ireland voting in a poll held for [these] purposes …”.

For a poll to be regarded as being held under the1998 Act, it is the Secretary of State who, by Order, is responsible for calling the poll, for setting the date, for specifying who is eligible to vote, and for setting the question (“or questions”) asked. There has been some debate in Northern Ireland as to whether the Northern Ireland Assembly might organise such a poll, but it is clear that, even if it can, it would be only advisory. A poll must be held in accordance with the provisions of the 1998 Act, if it is to have the legally binding effects set out subsequently.

The Secretary of State has a wide discretion as to when to hold such a poll but this discretion is, however, limited in two respects.  First, the Secretary of State is required to call a poll “if at any time it appears likely to him that a majority of those voting would express a wish that Northern Ireland should cease to be part of the United Kingdom and form part of a united Ireland.”  Second, the Secretary of State is required not to call a referendum “earlier than seven years after the holding of a previous poll” on the issue.

The domestic legal consequences of a vote in favour of exit depend on the exact nature of the question asked. There are two possible scenarios, at least theoretically. One possibility is that a question might be put on whether Northern Ireland should leave the United Kingdom and become a separate state (however unlikely this now seems, an independent Northern Ireland was debated on the fringes of loyalist politics in the past).  The more likely, second, scenario is that the question would ask whether Northern Ireland should leave the United Kingdom and form part of a united Ireland.

The domestic legal consequences of an affirmative vote for exit are not entirely clear because Section I addresses only the latter possibility. If there is an affirmative vote in favour of exiting the United Kingdom and joining a united Ireland, then the Secretary of State is under a duty to act on the result.  The Act specifies that where the wish expressed by a majority in such a poll is that “Northern Ireland should cease to be part of the United Kingdom and form part of a united Ireland” (but only in such circumstances, it would seem), then the Secretary of State “shall lay before Parliament such proposals to give effect to that wish as may be agreed between Her Majesty’s Government in the United Kingdom and the Government of Ireland.”

The second issue that Nick Barber’s post misses is the implications of international human rights law for Scottish independence.  This too is illustrated by the position in Northern Ireland, where the right to self-determination is accepted and agreed. There is no legal obligation under the 1998 Act on Parliament to accept these proposals.  Failure to do so, however, would be likely to result in a breach of the United Kingdom’s international law obligations to the Republic of Ireland under the Belfast Agreement.

In the British-Irish Agreement element of the Agreement, the two states recognised the legitimacy of whatever choice is freely exercised by a majority of the people of Northern Ireland with regard to its status, whether they prefer to continue to support the Union with Great Britain or a sovereign united Ireland.

They recognised also that it is for the people of the island of Ireland alone, by agreement between the two parts respectively and without external impediment, to exercise their right of self-determination on the basis of consent, freely and concurrently given, North and South, to bring about a united Ireland, if that is their wish, accepting that this right must be achieved and exercised with and subject to the agreement and consent of a majority of the people of Northern Ireland.

Most importantly, the two States accepted that a referendum under the Northern Ireland Act 1998 would have international law consequences on the British Parliament. The two states specifically affirmed that  “if, in the future, the people of the island of Ireland exercise their right of self-determination … to bring about a united Ireland, it will be a binding obligation on both Governments to introduce and support in their respective Parliaments legislation to give effect to that wish”.

This right to self-determination in the Irish context is merely one instance of a British constitutional law’s acceptance of the right to self-determination that the United Kingdom accepts as an international law obligation more generally. This can be seen, for example, in the United Kingdom’s ratification of the International Covenant on Civil and Political Rights and the International Covenant on Economic, Social and Cultural Rights.  Both these Covenants, binding on the United Kingdom in international law provide for a right to self-determination. This dimension appears to be entirely absent from Nick Barber’s post.

What the implications of these international law obligations are on British constitutional law is, of course, an immensely complicated issue, but the issue it raises is of importance for the Scottish (and British) debate more generally: when Nick Barber states a general moral principle that exit from the United Kingdom must take place according to UK constitutional law, does this adequately take into account the Scottish people’s (international law) right of self-determination?

Christopher McCrudden is Professor of Human Rights and Equality Law, Queen’s University, Belfast