Chapter one outlines how the relationship between war and the international legal order has evolved and introduces the idea of ‘complexity theory’ as a framework for understanding the events and issues considered in this book. Chapter two considers the pattern of events from the attacks on the US on 9-11 to the Iraq War 2003. Chapter three addresses the issues of law and morality involved in the War Against Terrorism and the War on Iraq. Chapter four focuses on the moral and legal debate around the War on Iraq and chapter five considers the systemic consequences for international law doctrine and practice, giving particular weight to US policy and approaches and how other states have responded to them. Chapter six appraises the post-war situation in Iraq in terms of political and economic organisation and human rights. It also assesses the consequences of the status of post-war Iraq for the wider region. Chapter seven concludes the book by examining the possible implications of the War Against Terrorism and the War on Iraq for world order in the twenty-first century.