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The judgment was soberly delivered, but its contents were brutal. Wearing a black dress with a large spider brooch, the president of Britain’s Supreme Court, Brenda Hale, announced that Prime Minister Boris Johnson’s decision to suspend Parliament this month was “unlawful, void, and of no effect.” All 11 judges agreed. There is no possibility of appeal.

Hale and her colleagues ruled that Johnson’s actions “had the effect of frustrating or preventing the ability of Parliament to carry out its constitutional functions.” In other words, by reducing the number of days Parliament could sit before October 31—the date Britain is legally due to leave the European Union—the prime minister had attempted to avoid scrutiny of his exit deal (or lack of one). The court’s decision means that Parliament can begin sitting again immediately. The House of Commons speaker has said that it will do so tomorrow.

By making such a high-profile ruling at such a febrile time, the court will be accused of taking a political stance—and of undercutting the executive’s ability to rule. Government lawyers argued during the case that the court was entering an “ill-defined minefield” that ought to be “forbidden territory.” It is a consistent theme of Brexit: The simple instruction delivered by the 2016 referendum—to leave the EU—has become a tortured process in which conflicting interests are proving impossible to reconcile.

Forbidden or not, this is certainly new territory. Britain’s Supreme Court is only 10 years old, and until Brexit came along, its rulings were not usually the subject of such intense scrutiny. That changed in January 2017, when it declared that former Prime Minister Theresa May could not pull Britain out of the EU without a vote in Parliament. After a lower court had come to the same conclusion, the powerful Daily Mail declared its judges “enemies of the people.” When the Supreme Court upheld the ruling, May was forced to take her proposed exit deal to the Commons. It was rejected three times, prompting her resignation.

Now, once again, the court has limited the powers of the prime minister. There is an echo here of the American conversation about impeaching Donald Trump. How should an established system deal with a populist politician who thrives on presenting himself as a man of action constantly undermined by outside forces? Trump is farther down this path: He clearly regards the normal constitutional safeguards as stifling and unfair restrictions on his personal power. To him, his interests and those of America are interchangeable. He is almost daring the rest of the political system to try to contain him, to give him an enemy to rail against. Johnson is pursuing a similar argument: First it was “the people versus Parliament,” and now it can be “the people versus unelected judges.”

There is a cascade of domestic consequences from the decision in Britain. First, it torpedoes a bad news cycle for the main opposition party, Labour, which has faced ridicule for the nebulous position on Brexit outlined at its party conference this week. Second, it means bills that were killed by the end of the parliamentary session have now been brought back to life. Third, it will allow the machinery of Parliament—such as select committees, urgent questions, and even speeches from the Commons floor—to be used to embarrass Johnson, not just over Brexit, but over an array of other stories, including allegations that he diverted public money to a close friend.

There are bigger implications, too. A sitting Parliament can make life harder for Johnson by pressuring him to bring back a new Brexit deal—or by forcing him to ask for an extension to the October 31 deadline. He has staked his political reputation on leaving the EU on that date “do or die,” but it is difficult to see how he can do so. Twenty-one of his own party defied him to vote to block a “no deal” exit, and there is little sign that he has a workable new deal ready.

All in all, the Supreme Court has handed a gift to the opposition, and turned up the heat on Johnson. Among Brexiteers, there have been suggestions that the court’s power is somehow illegitimate. Many of the senior figures in Johnson’s government are drawn from the Vote Leave campaign, which championed Brexit in 2016, and they have shown themselves willing to make populist arguments about the “will of the people.” With this ruling, Britain’s Supreme Court will be seen as stepping into politics in a similar fashion to its American counterpart. But unlike in the United States, Britain’s Supreme Court judges are appointed without political oversight, so there will again be whispers that “the establishment” is blocking Brexit, a measure backed by 52 percent of the voting population. In this worldview, the 2016 referendum result is a universal solvent for the awkward web of obligations that constrains the prime minister’s actions: to the remaining countries of the EU, to the Northern Irish peace process, to the sovereignty of Parliament.

Johnson’s reaction to the Supreme Court judgment will tell us if he sees his political project in similar terms to Trump. He told reporters in New York, where he is attending the United Nations General Assembly, that he strongly disagreed with the decision but would respect it. Although the government’s argument was that suspending Parliament was a routine procedure—nothing to do with Brexit—the prime minister added, “Let’s be in no doubt: There are a lot of people who want to frustrate Brexit. There are a lot of people who want to stop this country coming out of the EU.”

That coda reveals the uncertain place in which Britain now finds itself: with a prime minister who, thankfully, still obeys the law—while intimating that those who make and uphold that law are politically biased against him.

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