Global Constitutional Lawmaking Abstract This article identifies a nascent phenomenon of “global constitutional lawmaking” in a recent WTO jurisprudence which struck down a certain calculative methodology (“zeroing”) in the antidumping area. The article interprets the Appellate Body’s uncharacteristic anti-zeroing hermeneutics, which departs from a traditional treaty interpretation under the Vienna Convention on the Law of Treaties and the past pro-zeroing GATT case law, as a “constitutional” turn of the WTO. The article argues that a positivist, inter-governmental mode of thinking, as is prevalent in other international organizations such as the United Nations, cannot fully expound this phenomenon. Critically, this turn originates from bol...