Peter Quayle is an international lawyer, specialising in the law, governance and effectiveness of international organizations. His practice covers: 1. Governance Design and Reviews; 2. Ethics and Integrity Architectures; 3. International Administrative Law and Internal Justice Systems; and 4. Authorising Environments and Organizational Development. He advises international organizations across the world, including the African Development Bank Group, European Union, International Monetary Fund, United Nations and The World Bank.

Peter has also served as Executive Secretary at the Commonwealth Secretariat Arbitral Tribunal (since 2021), Chief Counsel, Corporate at the Asian Infrastructure Investment Bank (2016–2020), Associate Director, Senior Counsel at the European Bank for Reconstruction and Development (2012–2016) and Legal Advisor, Office of Foreign Litigation at the United States Department of Justice (2004–2012).

Peter was educated at the University of Oxford and University College London, is a solicitor-advocate of England and Wales, and an accredited workplace mediator. He lectures and researches on international organizations law, including at Harvard Law School (2025), the University of Cambridge (2021), Peking University (2017–2021) and the University of Notre Dame (2006–2017).

He is author of ‘Treaties of a Particular Type: The ICJ’s Interpretative Approach to the Constituent Instruments of International Organizations’, Leiden Journal of International Law (CUP, 2016); co-editor of 'Good Governance and Modern International Financial Institutions' (Brill Nijhoff, 2018); and editor of 'The Role of International Administrative Law at International Organizations' (Brill Nijhoff, 2020).