Now that the Tories have settled on a new Prime Minister, there is a fascinating constitutional question that must be addressed in Britain: Can Brexit be triggered unilaterally by the PM or must there be an Act of Parliament? This is not a trivial matter, because it is unclear whether a majority of MPs would support Brexit if it were put to a vote. (Let alone the House of Lords.)
The issue is partly about whether prior Acts of Parliament confirm or assume Britain’s EU membership in such a way that only another Act can repeal them. Another issue is whether the power to withdraw from a treaty (which is one way of thinking about Britain’s obligations to the EU) is part of the royal prerogative, which is the power that a PM can exercise without Parliament. In the United States, the President must get congressional approval for a treaty (either through 2/3 of the Senate or a majority of each House), but he can unilaterally abrogate. Is this true in the UK? I’m not sure what the recent precedents say, but we’ll find out.