This book explores how and why the UK left the European Union and its impact on the British Constitution. The British people voted to leave the European Union in 2016, decreeing a passage of historical significance with deep political and legal implications, as well as socioeconomic and geo-strategic consequences yet to be defined. The work explores the roots behind that decision, examining the political and legal steps that led to Brexit and analysing the consequences and prospects for the United Kingdom. It considers the ways that the British Constitution has faced the test of Brexit, and its constitutional, political and socioeconomic implications. It further examines the ways in which these implications interact in order to reconstruct a coherent and real constitutional framework. The book will be of interest to scholars and students in the fields of Constitutional Law, European Union Law, Political Science, Contemporary History, and International Trade.