Prime Minister has power to invoke article 50, Government lawyers advise

Parliament's authority is not needed for the Prime Minister to begin the formal process of withdrawing the United Kingdom from the European Union, Government lawyers have advised.

Oliver Letwin, the cabinet minister put in charge of preparing the negotiations for British withdrawal, disclosed the position yesterday to the House of Commons Foreigh Affairs Committee – while conceding that the matter is likely to be tested in court.

The question of the scope of the Government's powers in relation to article 50 has been extensively debated by public lawyers since the Brexit vote, with some maintaining that rights conferred by statute in relation to the EU treaties can only be removed by statute, while others take the view that the Acts giving effect to the treaties in domestic law do not affect executive powers recognised under international law.

Article 50 says that a member state may decide to withdraw from the EU "in accordance with its own constitutional requirements" – a matter left unclear for the UK due to its lack of a written constitution.

London legal firm Mishcon de Reya has begun proceedings on behalf of clients to have it declared that parliamentary authority is necessary. Mr Letwin claimed the question was "academic" because legislation would be needed to repeal the European Communities Act 1972. However the validity of the initial notice could be significant because of its effect in starting the two year time limit for agreeing terms of withdrawal.