In this lecture, Harold Koh addresses three questions: firstly, what does it mean to ask 'why do nations obey - as opposed to simply comply - with international law?'; secondly, how precisely do nations "internalize" or "domesticate" international law; and thirdly, how does understanding this process of internationalization help us to understand and promote national obedience to international norms? [While this article does not address women's human rights, it has been included on the WHRR because of the contribution it makes to the debate on the domestic implementation of international law.