Brexit: UK Supreme Court rules parliament is sovereign

Outcome of Dublin case could further complicate exit process

There was considerable, understandable disappointment in both Northern Ireland and Scotland on Tuesday at the unanimous ruling by the UK's Supreme Court that neither of their devolved assemblies is entitled to a decisive say on Brexit. The unsurprising decision makes clear once again the strictly limited nature of devolution – by no means a union of equals – and reiterates Westminster's primacy over their affairs.

"The devolution Acts were passed by parliament," Supreme Court president Lord Neuberger said, "on the assumption that the UK would be a member of the EU, but they do not require the UK to remain a member. Relations with the EU and other foreign affairs matters are reserved to UK government and parliament, not to the devolved institutions." Any other view would have posed huge challenges to prime minister Theresa May's government.

The logic of the court would suggest a similar view might be taken by it of the argument by some politicians that references to EU membership in the Belfast Agreement and related treaties might also somehow inhibit Brexit.

But if the ruling is a disappointment to proponents of real devolution, its substantive element – by a majority of eight to three – was nevertheless an important and most welcome reassertion of the primacy of parliament and the rights of the people against an ever-encroaching executive. That the government should seek to use the “royal prerogative” to assert its right to bypass an inconvenient parliament on the triggering of article 50 is hardly surprising. That it should be so vociferously supported by Brexiteers who have fought to restore Westminster’s writ over British law is bizarre.


The court echoed the high court in its reasoning that although the British government has the right to sign treaties without MPs’ consent, it could not do so if such treaties had been given effect through parliamentary legislation, as EU membership had been in 1972.

MPs will now get their say, and a Bill has been promised to authorise the triggering of article 50. It will almost certainly pass comfortably. How much influence MPs want to or will exercise through amendments to the Bill – the SNP has promised 50 – or while the two-year negotiations are under way, has yet to be fought out. It will be minimal if prime minister Theresa May has her way. They will, however, get to vote on the final package.

But the courts may not have had their final say. There is the matter of a case under way in the Dublin courts to ask the European Court of Justice to rule on whether article 50 is revocable once triggered. A finding that it is revocable might open up a whole new range of possibilities – even a second referendum – should May not get an acceptable deal from the other 27 member states.