The UK’s most senior judges ruled 8:3 that prime minister Theresa May does not have the power to trigger the formal process to begin the UK’s exit from the European Union.
The government appeal to the Supreme Court followed a High Court ruling in November that the prime minister did not have authority under Royal Prerogative to trigger Article 50 of the Lisbon Treaty, without the consent of Parliament.
The Supreme Court ruled that an Act of parliament is required. May now faces a fight to get emergency legislation through both houses of Parliament before the end-of-March deadline that she announced last week.
A fast-track Bill is believed to have already been drafted, the Evening Standard reported, but Brexit supporters fear some MPs will try to derail the legislation.
David Davis, Secretary of State for Exiting the European Union, said in the House of Commons that the government’s bill will be “the most straightforward one possible,” adding that the government’s end-of-March timetable still stands.
The judges ruled that the government does not need the consent of the devolved assemblies in Scotland, Northern Ireland and Wales to trigger Article 50. A majority of people in Northern Ireland and Scotland voted to remain in the EU in the referendum.
Delivering today’s ruling, Lord Neuberger said: “When the UK withdraws from the EU Treaties, a source of UK law will be cut off.
“Further, certain rights enjoyed by UK citizens will be changed.
“Therefore, the government cannot trigger Article 50 without Parliament authorizing that course.”
Neuberger said last June’s referendum had great political significance but said the act of Parliament drawn up for the vote did not say what should happen as a result.
“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.
“To proceed the other side would be a breach of settled constitutional principles stretching back many centuries.
“Subsequent events are entirely consistent with the proposition that the government has no power to withdraw from the EU Treaties without an authorizing act of Parliament.”
A summary of the ruling
All 11 Justices of the Supreme Court sat on the four-day hearing in December to mark the constitutional importance of the decision.
Lord Neuberger, Lady Hale, Lord Mance, Lord Kerr, Lord Clarke, Lord Wilson, Lord Sumption, and Lord Hodge backed the challenge to the government.
Three justices, Lord Reed, Lord Carnwath, and Lord Hughes, dissented in the judgment and agreed with the government.