The UN Convention on Transparency in Treaty-based Investor-State Arbitration (the "Mauritius Convention on Transparency") gained its first seven signatories at a ceremony in Port Louis, Mauritius on 17 March 2015.

The Convention’s purpose is to broaden the use of the new UNCITRAL Rules on Transparency in Treaty-based Investor-State Arbitration. These Rules are designed to provide a high level of transparency and public accessibility in investor-state disputes.

Under their own terms, these Rules apply only to UNCITRAL arbitrations that arise out of treaties "concluded" (i.e., typically, signed) after 1 April 2014. As the vastly greater proportion of the roughly 3,000 investment treaties currently in force were concluded prior to this date, the Transparency Rules will be of extremely limited application for a very long time unless either the state parties to treaties or the parties to individual disputes adopt additional instruments to apply them.

The Mauritius Convention is an important means to expand the use of the Rules to treaties initiated under this enormous raft of pre–Transparency Rules treaties. It provides a simple mechanism to apply the Transparency Rules to any investor-State arbitration, whether or not initiated under the UNCITRAL Arbitration Rules, in which both the investor’s "Home State" and the Respondent "Host State" are parties to the Convention. The Convention allows state parties who do so to make a limited number of reservations, excluding the application of the Transparency Rules to disputes arising out of certain particular investment treaties, or to all arbitrations under a particular set of Rules, or to any arbitration in which that state is the Respondent state.

The Convention was adopted by the United Nations General Assembly last December (2014). Its first seven signatories are Canada, Finland, France, Germany, Mauritius, Sweden, the United Kingdom and the United States. However, it has not yet entered into force. This will first happen six months after the date that the first three signatories have deposited their instruments of ratification at the UN in New York.

Here is a copy of the URL of the official text of the treaty: Official UN text of Treaty