The High Court in London has ruled that lawmakers must vote on whether the country can start the process of leaving the European Union, known informally as "Brexit."
The November 3 ruling by the High Court -- made up of three of England's most senior judges -- means the government cannot trigger Article 50 of the Lisbon Treaty, formally notifying the EU of Britain’s intention to leave the bloc, on its own.
A government spokesman said it would contest the ruling at the Supreme Court.
"The country voted to leave the European Union in a referendum approved by Act of Parliament,” he said. “And the government is determined to respect the result of the referendum.”
Prime Minister Theresa May has said she would invoke Article 50 by the end of March.
The other 27 member states have said negotiations about the terms of Britain’s exit, due to last two years, cannot begin until Article 50 has been activated.