This discerning book examines EU migration and asylum polices in times of crisis by assessing old and new patterns of cooperation in EU migration management policies in the scope of third-country cooperation. The case studies explored reveal that there has been a clear tendency and strategy to move away from or go outside the decision making rules and institutional principles enshrined in the Lisbon Treaty to advance third country cooperation on migration management. It explores the implications of and effects of the adoption of extra-Treaty instruments and patterns of cooperation in the light of EU rule of law and fundamental rights principles and standards. The book, examines the ways in which the politics of migration crisis and their patterns of cooperation and legal/policy outcomes evidenced since 2015 affect and might even undermine EU's legitimacy in these policy areas. Constitutionalising the External Dimensions of EU Migration Policies in Times of Crisis will be a key resource for academics and students focussing on EU Law and migration more specifically. Timely and engaging, it will also appeal to policy- makers, legal practitioners and international organisation representatives alike.