LONDON – United Kingdom’s Supreme Court ruled on Tuesday that Prime Minister Theresa May must get approval from parliament before triggering Britain’s formal exit from the European Union (EU), international media reported.

The SC rejected the government’s argument ruling that the PM cannot use executive powers under Article 50 of the EU’s Lisbon Treaty without getting approval of parliamentarians.

However, the court dismissed arguments that the UK’s devolved assemblies in Northern Ireland, Scotland and Wales should give their consent before Article 50 is invoked.

“The referendum is of great political significance, but the Act of Parliament which established it did not say what should happen as a result,” said President of the Supreme Court, David Neuberger.

“So any change in the law to give effect to the referendum must be made in the only way permitted by the UK constitution, namely by an Act of Parliament.”

Theresa May has repeatedly said she would invoke the Article 50 before the end of March but she will now have to seek the assent of lawmakers first.