The U.K. High Court’s ruling Thursday that the government does not have the authority to invoke Article 50 of the Lisbon Treaty—the formal mechanism that would begin negotiations for the country’s departure from the European Union—is a blow to Prime Minister Theresa May. The ruling, which the government says it will appeal to the Supreme Court, contends that doing so without seeking parliamentary approval, which May had argued was within her power, would effectively erode parliament’s sovereignty, which is enshrined in U.K. law. In other words: U.K. lawmakers must vote on whether to invoke Article 50.
This puts the government in an awkward position. Her predecessor as prime minister, David Cameron, had staked his political future letting voters decide on the U.K.’s continued membership in the EU. And despite dire warnings about the economic and social costs of Brexit, polls remained close and tightened during the final days. Still, Cameron and others—even those championing Brexit—suspected the “Remain” side would eventually triumph in the June 23 referendum. But it wasn’t even close: 52 percent voted to leave versus 48 percent who wanted to stay. Cameron resigned as prime minister and, subsequently, as a member of Parliament. After much political jockeying, and backstabbing, among the more high-profile proponents of Brexit within Cameron’s Cabinet, May, who had tepidly supported “Remain,” emerged as the candidate to replace him. As prime minister, she said she would respect the wishes of the voters, stacked her Cabinet with prominent “Leave” campaigners, and said that she would invoke Article 50 in March 2017, thereby setting in motion an expected two-year process to negotiate the U.K.’s future relationship with the EU.