Mauritius Convention on Transparency

The United Nations Convention on Transparency in Treaty-based Investor-State Arbitration, commonly called the Mauritius Convention on Transparency, was adopted by the UN General Assembly on 10 December 2014 (resolution 69/116) and opened for signature in Port Louis, Mauritius, on 17 March 2015. It entered into force on 18 October 2017, six months after the third ratification.

The Convention is a vehicle for extending the UNCITRAL Rules on Transparency in Treaty-based Investor-State Arbitration (in force 1 April 2014) to the large stock of investment treaties concluded before that date. By default, the UNCITRAL Transparency Rules apply only to arbitrations brought under investment treaties signed on or after 1 April 2014. Without the Mauritius Convention, applying the Rules to older treaties would require renegotiating each one individually — an impractical task given more than 3,000 bilateral investment treaties in existence.

The Transparency Rules themselves require, among other things:

• publication of key documents (notice of arbitration, pleadings, awards);
• open hearings;
• the possibility of written submissions by third parties and non-disputing treaty parties.

A state that ratifies the Mauritius Convention consents, on a reciprocal basis, to apply these rules to arbitrations under its existing investment treaties, subject to reservations expressly permitted by Article 3 (for example, excluding specific treaties or specific arbitral rules).

Uptake has been modest. Early ratifying parties included Mauritius, Canada, Switzerland, and Cameroon; signatories have included the United States, the United Kingdom, France, Germany, and Finland, though several have not ratified. The Convention is closely associated with broader debates on legitimacy in investor–state dispute settlement (ISDS), alongside UNCITRAL Working Group III reform discussions and the EU's push for an investment court system.