United Nations Convention on Transparency in Treaty-based Investor-State Arbitration (New York, 2014) (the "Mauritius Convention on Transparency")

Date of adoption: 10 December 2014

Entry into force: 18 October 2017

For up-to-date information about the parties to the Convention as well as signatories, see the status page.


The Convention is an instrument by which Parties to investment treaties concluded before 1 April 2014 express their consent to apply the UNCITRAL Rules on Transparency in Treaty-based Investor-State Arbitration ("Rules on Transparency" or "Rules"). The Rules on Transparency, effective as of 1 April 2014, are a set of procedural rules for making publicly available information on investor-State arbitrations arising under investment treaties. In relation to investment treaties concluded prior to 1 April 2014, the Rules apply, inter alia, when Parties to the relevant investment treaty agree to their application. The Convention is an efficient and flexible mechanism for recording such agreement.

Key provisions

The Convention supplements existing investment treaties with respect to transparency-related obligations. Article 2, a key provision of the Convention, determines when and how the Rules on Transparency shall apply to investor-State arbitration within the scope of the Convention. In contrast to the Rules on Transparency, whether the arbitration is initiated under the UNCITRAL Arbitration Rules or not does not have any impact on the application of the Convention. The general rule of application is stipulated in paragraph 1 (bilateral or multilateral application) and paragraph 2 refers to the application of the Rules on Transparency when only the respondent State (and not the State of the investor-claimant) is a party to the Convention (unilateral offer of application).

A Party to the Convention has the flexibility to formulate reservations, thereby excluding from the application of the Convention a specific investment treaty or a specific set of arbitration rules other than the UNCITRAL Arbitration Rules (negative-list approach). A Party may also declare that it will not provide a unilateral offer of application. Lastly, in the event the Rules on Transparency are revised, a Party may also declare, within a limited period of time after such revision, that it will not apply that revised version. By defining specific timing for the formulation and withdrawal of reservations, the Convention provides the necessary level of flexibility, while ensuring that reservations cannot be used to defeat the purpose of the Convention.

The Convention and any reservation thereto apply prospectively, that is to arbitral proceedings commenced after the entry into force of the Convention for the Party concerned.

Together with the Rules on Transparency, the Convention takes into the account both the public interest in such arbitration and the interest of the parties to resolve disputes in a fair and efficient manner. The Convention foresees the Secretary-General of the United Nations as performing the repository function, through the UNCITRAL secretariat (see the Transparency Registry).