A British court ruled on Thursday that the government needs parliamentary approval to start the process of leaving the European Union, potentially delaying Prime Minister Theresa May's Brexit plans.
The government said it would appeal against the High Court ruling and Britain's Supreme Court is expected to consider the case early next month.
A spokeswoman for May said the prime minister still planned to launch talks on the terms of Brexit by the end of March and added: "We have no intention of letting this derail our timetable."
The pound, which fell sharply after Britons voted to leave the EU by ۵۲ to ۴۸ percent on June ۲۳, rose after the ruling.
Many investors took the view that lawmakers would now be able to temper the government's policies, making it less likely that the government would opt for a "hard Brexit" -- a scenario in which it prioritizes tight controls on immigration over remaining in the European single market.
The High Court ruled that the government needs parliament's backing to trigger Article ۵۰ of the EU's Lisbon Treaty, the formal step needed to start the process of exiting the bloc.
"The most fundamental rule of the UK's constitution is that parliament is sovereign," said Lord Chief Justice John Thomas, England's most senior judge.
Thomas and two other senior judges did not spell out in their ruling whether the government would need to pass a new law to begin the divorce proceedings, but Britain's Brexit minister David Davis said this was likely if the Supreme Court upheld the decision.
"The judges have laid out what we can't do and not exactly what we can do, but we're presuming it requires an act of parliament," Davis told BBC TV.