Roberts, AntheaJohn, Taylor St2026-01-132026-01-130938-5428https://hdl.handle.net/1885/733804204In recent years, several proposals by states to reform or displace investor-state dispute settlement (ISDS) have gained prominence. While many factors shape which reform proposals states support, here we focus on one important, but often overlooked, factor: the 'insider' or 'outsider' status of the government officials who formulate states' proposals. Based on five years of para-ethnographic observation and interviews with officials involved in ISDS reform, and informed by the interdisciplinary innovation literature, we explore how individuals who have not spent their careers within the field of investment arbitration (and are perceived as 'outsiders' by those within that field) have developed more disruptive reform proposals while arbitral insiders have typically proposed sustaining reforms. We illuminate these dynamics in the ISDS reform debates with case studies of four actors: the USA, the European Union, Bahrain and Brazil.Support for writing this article came from the Norwegian Research Council, Project no. 276009, and the Australian National University Futures Scheme. Funding to follow the UNCITRAL Working Group comes from a capacity-building project funded by the Australian Department of Foreign Affairs and Trade.application/pdfen-AU© 2023 The Author(s)https://creativecommons.org/licenses/by-nc/4.0/202210.1093/ejil/chac0652023-10-22Creative Commons Attribution-NonCommercial License