The High Court in London stunned analysts Thursday by halting the British government's efforts to carry out the will of the people as reflected earlier this year in the highly contentious Brexit referendum, in which a narrow majority voted to leave the European Union.
The court ruled that Prime Minister Theresa May lacks the legal authority to act without parliament, meaning she will need the consent of lawmakers to formally initiate the process whereby the United Kingdom can jettison its ties to the EU – that is, if the ruling is not overturned on appeal.
"It is one of the most important constitutional court cases in generations. And the result creates a nightmare scenario for the government," correspondent and political analyst Eleanor Garnier wrote for the BBC.
Ms. May had said she would trigger Article 50, the EU departure mechanism, by March at the latest, but Thursday's decision muddles that plan and places her in direct conflict with members of parliament, most of whom opposed Brexit in the run-up to the vote. If the government appeals to the Supreme Court, the proceedings could last well into 2017, as The Washington Post reported.
Attorneys for the government had argued that May could exercise her prerogative powers to carry out the referendum result, but the lord chief justice, Lord Thomas of Cwmgiedd, shot down that argument as part of a three-judge panel, as The Guardian reported.
"The court does not accept the argument put forward by the government," the lord chief justice wrote. "There is nothing in the 1972 European Communities Act to support it. In the judgment of the court, the argument is contrary both to the language used by parliament in the 1972 act, and to the fundamental principles of the sovereignty of parliament and the absence of any entitlement on the part of the crown to change domestic law by the exercise of its prerogative powers."
To put it bluntly, the justice added: "The government does not have power under the crown’s prerogative to give notice pursuant to article 50 for the UK to withdraw from the European Union."
Liberal Democrat leader Tim Farron praised the ruling as an important step to ensure that the UK does not rush into a poorly structured Brexit arrangement.
"Given the strict two-year timetable of exiting the EU once article 50 is triggered, it is critical that the government now lay out their negotiating to parliament, before such a vote is held," he told The Guardian.
But the decision drew ire from some in the pro-Brexit camp, including Independence Party parliament member Nigel Farage, who tweeted that he fears opponents will make every effort to block an Article 50 notification: "They have no idea level of public anger they will provoke."
Gina Miller, a lead claimant in the case challenging the government's Brexit plan, said the court made the right decision to preserve parliamentary sovereignty.
"It was not about winning or losing. It was about what was right," she told The Guardian. "Now we can move forward with legal certainty."
And for fellow lead claimant, hairdresser Deir Dos Santos, the case was never about challenging the results of the referendum. He voted in favor of leaving the EU.
"But I did not think it was right for the government then just to bypass parliament and try to take away my legal rights without consulting parliament first," Mr. Santos said.
The government says it will appeal, with further court hearings expected next month.