The EU was created with the aim of promoting an ever-closer union among the peoples of Europe. For decades, the European project has been consolidated to the extent that new countries have joined the EU and its supranational governance areas have been gradually increasing. In the period between 2010 and 2020, the context changed drastically. In that period there have been crises that differ from all the previous ones that have jeopardized the European integration process. Despite decades of research in the field of European integration, as of the date of writing this book, academic studies assessing European disintegration are profoundly scarce. This investigation addresses, from the perspective of public international law, the consequences of the eurozone crisis, migration crisis, Brexit, and the war in Ukraine to shed light on whether there have been any signs of European disintegration and provide readers with a set of explanatory factors that show different results for each crisis.