The U.K.'s exit from the European Union must be triggered by Parliament, not by the prime minister, the nation's Supreme Court says. In an 8-3 ruling, the court ruled that Theresa May doesn't have legal standing to carry out Brexit, the plan to leave the EU that voters embraced in a close referendum last June.The prime minister's office says the ruling "does nothing to change" its timetable of leaving the economic union by the end of March. That's when May set a deadline for invoking Article 50 — the exit clause that's built into the EU's constitutional rules. But the already complicated process, the Supreme Court now says, must also include Parliament."The ruling is an embarrassing setback for the prime minister, but it does not threaten to derail Brexit," NPR's Frank Langfitt reports from London. "Ministers of Parliament can delay the bill and debate it, but they can't overturn the June referendum."The ruling bolsters a High Court ruling from November, which Prime Minister May's government had appealed. It's also a victory for Gina Miller, a leading plaintiff in the case who works as an investment manager.Saying that her case was about the legal process, Miller said after today's ruling, "No prime minister, no government, can expect to be unanswerable or unchallenged."In an interview with NPR last year, Miller explained her reasons for challenging the government's plan to leave the EU: