The Legality of Downgrading Nationally Determined Contributions under the Paris Agreement: Lessons from the US Disengagement

27 October 2017
New Journal Article by Lavanya Rajamani and Jutta Brunnée

Abstract: In this analysis piece, we consider a legal question that generated much debate in the lead-up to the US decision to withdraw from the Paris Agreement: can a Party downgrade its nationally determined contribution (NDC) to climate mitigation without running afoul of its treaty commitments? Drawing on the treaty interpretation methods set out in the Vienna Convention on the Law of Treaties, we examine the Paris Agreement’s normative framework and analyse the provision on adjustment of NDCs. We show that, while NDCs as such are not legally binding, they are subject to binding procedural requirements and to normative expectations of progression and highest possible ambition. Read together, these binding and non-binding terms make plain that a Party would contravene the spirit of the Paris Agreement if it downgraded an existing NDC. The US federal government is already scaling back its domestic climate action, such that it is unlikely to meet its NDC. Its Paris withdrawal, however, can only be formally declared in 2019 and will not take effect until 2020. We consider how, during this interim period, the legal implications of the ‘withdrawal’ approach differ from those of the ‘stay-and-downgrade’ approach.

The full paper is available on the OUP Academic website, subject to access restrictions. For a copy of the paper, please write to Lavanya Rajamani at

An earlier question-and-answer blog with Lavanya Rajamani on Trump's announcement to withdraw from the Paris Agreement can be accessed here.

The views shared belong to individual faculty and researchers and do not represent an institutional stance on the issue.