The process of leaving the EU was initiated by a referendum held in June 2016 which resulted in 52% voting in favour of British withdrawal. In October 2016, the British prime minister, Theresa May, announced that Article 50 would be invoked by "the first quarter of 2017". On 24 January 2017 the Supreme Court ruled in the "Miller" case that the process could not be initiated without an authorising Act of Parliament, and unanimously ruled against the Scottish Government's claim in respect of devolution. Consequently, the European Union (Notification of Withdrawal) Act 2017 empowering the prime minister to invoke Article 50 was enacted in March 2017.