Transparency in investment treaty arbitration: past, present, and future

This contribution to the special collection analyses transparency in international investment treaty arbitration. It charts the development of transparency in investment treaty arbitration, highlighting how developments in approaches to the transparency of arbitral proceedings track broader evolutions within investment treaty arbitration itself. The article first outlines how 'transparency' has been achieved over time through key procedural rules and treaties. It next explores the different objectives associated with transparency reform efforts and measures, examining the possible links between the transparency of arbitral proceedings and improved outcomes in treaty and arbitration practice, the accountability of decision-makers, and public trust and legitimacy in the arbitration system more broadly. Against this backdrop, the article focuses on the different understandings of 'transparency' that underpin key measures and reform efforts. It examines, in particular, transparency as 'availability', 'accessibility', and 'participation'. The article concludes by examining the close link between transparency and the development and future of investment treaty arbitration. It highlights, in particular, the pivotal role that transparency measures have played in creating a burgeoning system of 'precedent', engaging public attention, and prompting the creation of innovative amendment structures that could be applied to implement other reforms in the future.