In the past decade, numerous military operations by outside states have relied on the real or alleged 'invitation' of one of the parties. In this book, three experts examine the relevant legal issues, from sovereignty to the scope and relevance of consent, the use of force to the role of the Security of Council. Using critical historical analysis, qualitative case studies and large-N empirics, these topics are debated and addressed in a unique trialogue format. Accommodating the pluralism of the field, the trialogical setting highlights the divergences and commonalities of each of the three approaches. Benefiting from an in-depth analysis of recent cases of armed intervention and the diversity of the authors' perspectives, this collection is key to developing a richer understanding of the law of military intervention. This title is also available as Open Access on Cambridge Core.