The Belfast Agreement stipulates that if "at any time it appears likely" to a secretary of state that a majority of those voting in Northern Ireland "would express a wish for a united Ireland", they are obliged to call a referendum. But that is not an acceptable logic to London in the case of Scotland. Boris Johnson insists that another generation must pass before the Scots may vote again on independence.
Yet in the six years since it voted narrowly to remain in the union, the political landscape has changed significantly. The UK has left the EU against the wishes of the majority of the Scottish people, and on terms which are seen to distinctly advantage Northern Ireland over Scotland. And the fight against coronavirus has seen the Scottish government inspire greater confidence than London. Polls are showing majorities in favour of a new referendum and of independence.
Now Scotland's first minister Nicola Sturgeon has said she will hold one if her Scottish National Party wins a majority in May's Holyrood elections, regardless of Westminster's consent. If it wins, the SNP will request from Westminster a section 30 order which, under the Scotland Act 1998, allows Holyrood to pass laws normally reserved to Westminster. If not forthcoming the SNP government would introduce a bill allowing a "legal referendum" and would "vigorously oppose" any legal challenge from London. Sturgeon, under party pressure to be more aggressive on independence, has pushed the ball back into the UK court although she has not said she will defy any eventual court order. She would also have the option of an advisory vote.
International law on the right to self determination is evolving. It recognises the entitlement of substantial national entities to secede and requires central governments to negotiate in good faith when such aspirations are clearly manifest. Whatever the merits of that, however, the issue will not go away and Westminster would be better advised to engage constructively and imaginatively on the nature of Scotland’s place within the UK. Avoidance is not a sustainable strategy.