Bringing ethical inquiry into international law

International law and ethics share a common goal of helping us understand the norms and institutions needed to promote a just world order. Yet each of the two fields has approached this shared task with little regard for the insights of other, and interdisciplinary collaboration is now imperative. This essay shows the complementary nature of inquiries in political and moral philosophy, on the one hand, and international law, on the other, by examining the so-called New Haven School (or policy-oriented jurisprudence), an international law method that explicitly considers values as both inputs and outputs of the process of making law. It finds that the School’s sociological orientation does not adequately integrate ethical inquiries essential to prescribing law, in particular questions about the scope of duties that individuals and states owe those abroad. Using the current legal debate over the extraterritorial application of human rights as an example, the paper shows how approaches from moral and political philosophy can help provide a rigorous and principled basis for the prescription of law, as well as link seemingly unrelated questions of international law to each other.