LONDON (REUTERS) - Britain's Supreme Court said it will deliver its ruling next Tuesday (Jan 24) on whether Prime Minister Theresa May can begin the process of leaving the European Union without Parliament's assent.

Mrs May has said she would trigger Article 50 of the EU's Lisbon Treaty, the formal means of exiting the bloc, by the end of March and that the government could act without needing lawmakers' approval.

However, London's High Court decided last November that it would be unlawful for Mrs May to trigger Article 50 alone using executive powers known as "royal prerogative".

The government appealed against that ruling to the Supreme Court, Britain's highest judicial body, which held four days of hearings last month.