In this fresh, objective, and non-argumentative volume in the Elements of International Law series, Peter Hongler combines a comprehensive overview of the technical content of the international tax law regime with an assessment of its crucial relationship to wider international law. Beginning with an assessment of legal principles and foundations, the book considers key general principles, treaty based regimes, and regional integration in tax matters. In the second half of the work Hongler places international tax law in the context of its wider relationships with human rights law, and trade and investment law. He concludes by considering major legal successes and failures and what might be done to address these.