‘On the legal front, the current debate focuses on the question of who has the legal authority to trigger Article 50 of the Lisbon Treaty and begin the Brexit process. Some argue (quite convincingly) that only Parliament has this authority (and see Barber, Hickman, and King’s post). Others argue that Government, and in fact the Prime Minister, acting under the Royal Prerogative, can act without the approval of Parliament. The latter is, apparently, the view of Government’s lawyers.’
UK Constitutional Law Association, July 2016
Source: www.ukconstitutionallaw.org