After agreement On the authority and legitimacy of environmental post-treaty rules

A vast and complex web of environmental ‘post-treaty rules’ (PTRs) has become central to developing international environmental governance. These PTRs include resolutions, recommendations, decisions, guidelines, principles and modalities adopted in the aftermath of Multilateral Environmental Agreements (MEAs) by Conferences and Meetings of the Parties (COPs and MOPs). But where, how and over whom do these hundreds of instruments wield authority? Are they mere ‘political commitments’ between government representatives? Or do they create legal obligations? Can governments invoke them against individuals and companies? And are these rules increasing or decreasing environmental protection? This study answers such questions by applying a theoretical framework of authority and legitimacy to the post-treaty rules of four international environmental treaty regimes – on wetlands, trade in endangered species, the ozone layer and climate change. In doing so, it aims to enable international (environmental) lawyers to gain a better grasp on this important subject, while raising awareness among practitioners of the vulnerabilities of the PTR practice. A key finding is that the authority of post-treaty rules is sharply compartmentalized between the regimes where they originate (high authority), and the international legal order and the national legal orders (low authority). The study suggests that this difference is due to the strong reliance of PTRs’ authority on legitimacy beliefs, rather than legal obligation. This comes at a cost of fundamental procedural principles. It finds that PTRs’ main asset over treaty amendments – their flexibility – is a liability too, because it facilitates diminishing past gains as well.