Over recent decades, international humanitarian law has been shaped by the omnipresence of so-called expert manuals. Astute and engaging, this discerning book provides a comprehensive account of these black letter rules and commentaries produced by private expert groups and demonstrates why the general acceptance of these expert manuals is largely unjustified. This theoretically grounded book bridges the divide between theory and practice by linking legal theory to the doctrinal and practical concerns of the laws of war. The author innovatively links interdisciplinary insights to the needs of military lawyers in practice, showing the pitfalls of relying on private manuals as arguable restatements and interpretations of the law 'as it is'. At the same time, he explains why expert processes are so successful and why this should be of concern to all of us. Stimulating and challenging, this book will prove essential reading for students and scholars of public international law, legal theory, and those focussing on the laws of war more specifically. Its practical approach will also greatly benefit legal practitioners working in the field of military law.