Why we need a new Act of Union — and what to put in it

For the last century the United Kingdom has regarded itself as a voluntary union of four home nations. Consent, rather than the force of law, has been the glue that has held us together. This is not normal. Most countries hold themselves together with something rather more robust.

In Spain, the courts, applying the constitution, ruled that it was unlawful for Catalan separatists even to hold a vote on Catalan independence. In the United States the position would be even stricter. Its leading case on the law of secession was admittedly decided in the immediate aftermath of the US Civil War, but the US Supreme Court’s authoritative decision on the matter was unequivocal. When a state becomes one of the United States it enters into ‘an indissoluble relation’ that is ‘final’, the Court ruled. There is ‘no place for reconsideration, or revocation, except through revolution’ or with the consent of the United States.