The making of international trade law in the WTO has developed mostly by means of primary lawmaking, i.e. by means of treaty. WTO treaty-making is supplemented by the accession protocols of new Members that may modify the set of rights and obligations between the acceding WTO Member and existing ones and/or contain ‘WTO-plus’ type obligations for the acceding Member. WTO treaty obligations may also be modified by means of amendment, authoritative interpretation, subsequent agreement and subsequent practice, or WTO Members’ use of the general waiver power. Secondary lawmaking within the institutional framework of an international organisation like the WTO comes about through the adoption of rules arising from decisions of the organisation, or one of its institutional bodies, that have normative effect. Delegated lawmaking – albeit somewhat putative – and waiver decisions as secondary legal acts can be considered as the two main forms of secondary lawmaking in the WTO.