Customary international law: A transformative force in the landscape of IHL

Abstract

This chapter demonstrates that custom has played a fundamental role in the making and shaping of international humanitarian law ever since the branch of law came into existence. It focuses on the relationship between treaty norms and customary norms today, in terms of the norms themselves and the methodology used to ascertain or interpret them. It reviews customary international humanitarian law's influence on the manner in which customary international law is understood and ends by reflecting on the way in which customary international humanitarian law in this area might develop, considering some of the methodological challenges, puzzles, and dilemmas that it has faced over recent years.