Supreme Court Brexit ruling: the legal wrangles are just beginning

Gina Miller, lead claimant in the Article 50 case ©Victoria Jones/PA Wire/PA Images

In its judgment in the Miller case, delivered this morning, the Supreme Court ruled that the government could not trigger Article 50 without an act of Parliament. The government had argued that it could use prerogative powers—the rag bag of executive powers left over from Britain’s days as an absolute monarchy—to begin the withdrawal process from the EU. But the Court proved itself the true guardian of parliamentary sovereignty by insisting that the process for Brexit depended on parliamentary consent.

In the turbulent months after the referendum, there seemed some promise that the intervention of the courts would bring order to the chaos and Brexit might be stopped, or at least delayed. But politics has moved on. After the High Court decision in November, Theresa May prepared a draft bill authorising the government to make the Article 50 declaration and the Supreme Court judgment no longer holds momentous political significance. No doubt that’s why Liz Truss felt able to issue an unusually gracious statement praising the independence an integrity of the judiciary.

There was some speculation, following extra-judicial comments by Brenda Hale, Deputy President of the Supreme Court, that the judges would direct the form that the legislation should take. That was always unlikely—after all, this was a decision about parliamentary sovereignty—and the judges held that "what form such legislation should take is entirely a matter for parliament." The bill can be as long, or as short, as the government desires. David Davis has said it will be "straightforward," suggesting the government will opt for a short bill. It will need to follow the usual legislative process and obtain consent from both Houses of Parliament, but its safe passage is almost certainly assured.

The most important implications of the judgment are likely to lie not in the conclusions on parliamentary sovereignty, but in the decision on devolution. The High Court did not consider arguments about the power of the Westminster Parliament over the devolved assemblies of Scotland, Wales and Northern Ireland. But when the government appealed the original decision, the devolution issues were referred to the Supreme Court by the Northern Irish Court of Appeal, and addressed by representatives for the governments of all the devolved administrations. This made the government's appeal risky. If the Supreme Court had ruled that the consent of the devolved assemblies—including Holyrood, where the fiercely anti-Brexit SNP are in charge—was required to trigger Article 50, Brexit would have been dead in the water. But the government’s gamble paid off and the Court found that the so-called “Sewel Convention” (by which the Westminster government agrees not legislate on devolved matters without the consent of the Scottish Parliament) was nothing more than a political convention that had no legal force. This is a legal victory the government will relish, but the political consequences may be dramatic. Nicola Sturgeon has already announced that the decision makes the need for Scottish independence even greater.

While today’s decision is unlikely to disturb the timetable for Article 50, it is only the beginning of legal wrangles over Brexit. There is already litigation underway in Ireland on the revocability of Article 50 (the Supreme Court did not express a view on the issue), which could establish that—as most lawyers believe—the UK could change its mind about Brexit even after pulling the legal trigger. Meanwhile, the High Court is due to consider a judicial review on leaving the European Economic Area, roughly the single market, as distinct from the EU. And when the government begins to try and untangle UK and European law, opportunities for legal challenge will be boundless. As Gina Miller has demonstrated, Remain voters are up for a fight.