LONDON – Britain's High Court has ruled that the prime minister cannot trigger the U.K.'s exit from the European Union without Parliament's approval — a decision that complicates an already confusing situation riddled with uncertainties.
The case, the first successful legal challenge since Britons voted in June to leave the 28-nation bloc, throws British Prime Minister Theresa May's plans for "Brexit" into turmoil because she may now have to contend with drawn-out debates in Parliament that could reveal her government's negotiating positions to EU officials.
Here is what we know — and don't know — about where Brexit stands now.
WHAT DOES THE RULING MEAN?
Three senior judges agreed that Britain's government does not have the power to trigger Brexit without first consulting Parliament. This means that May will need to let both the House of Commons and the House of Lords have a say before the government can trigger Article 50 of the EU's treaty, which kicks off the two-year talks for Britain and the EU to agree to the terms of their divorce. May had said earlier she would trigger the process before April.
WHAT HAPPENS NEXT?
Britain's government has confirmed it will go to the Supreme Court to appeal the ruling, and a hearing is expected to take place next month. If the appeal succeeds, Britain will go ahead with its timetable and activate Article 50 by the end of March.
If the government loses its appeal, however, May faces a headache because the majority of U.K. lawmakers backed the Remain camp. Now they would have the opportunity to impose numerous conditions on the terms of leaving and delay the government's exit plans by months.
CAN THIS STOP BREXIT?
It's unknown how exactly Parliament will have a say in the talks. The government may put a short "yes or no" vote to lawmakers on whether Britain can start the Brexit process, or — as Brexit Secretary David Davis has suggested — a new bill will be required, taking months to go through both houses of Parliament. Still, lawmakers are unlikely to flatly block Brexit because that would be seen as defying public opinion. Britons voted 52 percent to leave the EU in June's referendum, and Parliament is likely to respect the plebiscite.
CAN THIS LEGAL BATTLE DRAG ON?
Experts say it's possible — but extremely unlikely — that the case could be taken further to the European Court of Justice in Luxembourg, the EU's highest court.
Nick Barber, a constitutional law professor at Oxford University, says Britain's government cannot appeal if it loses at the country's Supreme Court. The EU court could become involved, but only if the Supreme Court decides to refer it there to study a point of EU law.
"I can't see anybody wants to see it go to the European Court of Justice. I think all sides would agree that would be a mess," Barber said.