Gina Miller, lead claimant in the case, outside the High Court this morning ©Dominic Lipinski/PA Wire/PA Images What denouement could be more appropriate to a campaign about Taking Back Control than a United Kingdom court ruling that, as a matter of United Kingdom constitutional law, MPs elected in the United Kingdom should decide whether, and under what conditions, to trigger Article 50? That’s what the High Court today decided. But what, in practice, does it mean? In early December the Supreme Court will hear the government’s appeal. And it is possible that the government could change its position. It could advance a case—the exact opposite of that which it advanced before the High Court—that Article 50 is reversible. To do so would give the government better prospects of succeeding in its legal arguments but it would carry a heavy political cost. The government would, in effect, be saying that the referendum campaign is not over. It would be acknowledging we may not, after all, choose to leave the EU. Brexit would no longer mean Brexit. That, even the most ardent Remainer would acknowledge, is an unlikely stance for the government to take. But given the nature of the High Court decision, absent such a damaging volte-face, the government can have little confidence about the outcome of the Supreme Court appeal. The government will know this and so, alongside the Supreme Court appeal, it will be drafting a Bill in readiness for it to go before parliament. That Bill, it is tolerably clear as a matter of constitutional law, would have to pass both Houses: the Commons and the Lords. There would in the Commons be—and I think, rightly—little or no enthusiasm for rejecting such a Bill. The fact that, legally, the referendum was not binding does not have as a consequence that, politically, it can or should be ignored. But it is very possible—indeed it is likely—that MPs will seek to impose conditions on the government’s decision to trigger Article 50. Those conditions are likely to be a mix of procedural and substantive. The procedural conditions may include a requirement that government presents its negotiating strategy to parliament in advance of triggering Article 50; that it regularly reports to parliament on the progress of negotiations; and perhaps even that it gives to parliament the final say over whether to accept the outcome of those negotiations. The substantive conditions may include setting the government’s negotiating priorities—and a requirement that the outcome meets certain economic objectives. Remember Gordon Brown’s Five Economic Tests for joining the Euro? And this is entirely appropriate. The people may have voted for Brexit but they did not say what Brexit means. The complex job of unpicking that meaning—mindful of the views of the whole electorate, for the referendum was not a vote to exclude the 48 per cent from participating in the shaping of the future of their country—must be for our elected parliament rather than for a Prime Minister whose personal democratic mandate as Prime Minister is weak indeed. I hope that the House of Commons will impose those conditions. But if they will not, I believe that the House of Lords will. In practical terms it is difficult to contemplate that these steps—drafting a Bill, debating it in the Commons, voting on amendments, placing it before the House of Lords and then addressing amendments introduced by the Upper Chamber in the Commons again—can sensibly be taken in the short interregnum between the handing down of the Supreme Court’s decision (presumably in late December) and the end of March. So, whatever else the decision means, unless the Supreme Court overturns the High Court’s decision, it is unlikely that Theresa May will be able to adhere to her promise to trigger Article 50 by “the first quarter of 2017.” On the 17th of November, Prospect launched Brexit Britain: the trade challenge. A publication designed to act as a guide for parliamentarians, officials and businesses with a stake in the UK’s changing relationship with the world following Brexit. To see the complete contents of the report please click here. For speaker and partnership opportunities, please contact firstname.lastname@example.org. You can also receive the full “Brexit Britain: the trade challenge” report as a fully designed PDF document. To do so, simply enter your email below. You’ll receive your copy completely free—within minutes.