Public Participation: Amicus Curiae in International Investment Arbitration

Public Participation: Amicus Curiae in International Investment Arbitration

This guide explains what amicus curiae participation is in the context of international investment arbitration. In addition, it outlines who can participate, what such participation entails, why participation may be beneficial, and lastly, the different procedural rules governing participation in different fora. Author: Inu Manak

What is amicus curiae participation?

As “friends of the court,” amici curiae participate in arbitration proceedings as third parties to the dispute. However, this status is not the same as a party to the dispute itself; instead, amici curiae provide submissions on the matter at issue that they have an interest in, and allows them to raise perspectives that may differ from what is presented by the parties to the dispute. In this way, amici curiae ensure that the arbitration tribunal has the opportunity to hear from third parties that have a stake and expertise in the matter at issue, and can provide information that can assist in the dispute proceedings.

Who can participate and what does it entail?

Individuals, non-governmental organizations (NGOs), industry representatives, and other parties with an interest in the dispute can request to participate as amici curiae.

Generally speaking, amici curiae are not granted specific status and do not have special rights such as access to the dispute proceedings, access to documents submitted by the disputing parties, or the ability to provide an oral submission. In the majority of circumstances, the extent of participation for amici curiae is to share a written submission. There are exceptions to this, of course, which are decided on a case by case basis.[1] For ICSID tribunals, Rule 32(2) allows the disputing parties effective veto rights over whether a non-disputing party can have access to the hearings.[2] UNCITRAL arbitration rules are explicit that hearings are to be held in camera (meaning, in private) “unless the parties agree otherwise.”[3]


[1] For example, Piero Foresti v South Africa, ICSID Case No. ARB(AF)/07/01, where NGOs were granted their request for amici curiae, including access to key documents submitted by the parties to the dispute.

[2]  ICSID Convention Arbitration Rules, Arbitration Rule 32(2), accessed July 7, 2016,

[3] UNCITRAL Arbitration Rules (with new article 1, paragraph 4, as adopted in 2013), Rule 28(3), accessed July 8 2016,

Why participate as amici curiae?

Participating in investment arbitration as amici curiae has benefits not only for the third party participants, but also for the arbitration system as a whole. Inviting the submissions of parties that are not direct disputants allows for a wider range of opinions to be heard, which is important because it is rare that a specific case will not touch upon issues that are highly relevant for other investors or host states around the world. Essentially, it is a fairly simple way to participate in investment arbitration and provide broader input and perspective on the issue at dispute. Participating thus increases the legitimacy of investment tribunals and potentially the quality of the decisions by ensuring that all stakeholders have the opportunity to be heard and submit arguments and information that the disputing parties may not have considered, or were not applicable directly to them, but may be to others.

Some have also argued that “amicus curiae participation can promote a general interest in procedural openness and ensure that the broader public does not perceive the arbitration process as `secretive´.”[1] In fact, this type of participation is one way to address transparency concerns over investment arbitration because it brings attention to cases, which can increase public awareness and knowledge of the dispute process, and also serve as a mechanism to alert other potentially interested third parties of their stake in the dispute.

However, since there is no rule explicitly stating that investment arbitration tribunals must take the facts and arguments presented in amicus curiae submissions into account, some have argued that the value of amici curiae participation is not as strong as it could be.[2] For instance, in Biwater Gauff v Tanzania, which is often cited as “a model for intervention,” the amicus curiae submission “appears to have had little or no impact on the tribunal’s reasoning.”[3] Despite this, participation as amici curiae is still a worthwhile endeavor, particularly because such participation has been relatively recent, and growing over time. In fact, the recent case Philip Morris v. Uruguay (ICSID Case No. ARB/10/7) illustrated how an amicus brief submitted by an international organization, in this case, the World Health Organization (WHO) could have a substantial impact on the final decision.

As such, it may be too early to tell what effect amici curiae participation will have on the investment arbitration system in the future. In addition, growing concerns over transparency point to a demand for such participation, and may result in tribunals becoming more sensitive to these requests in order to sustain their legitimacy in the face of criticism.


[1] Eugenia Levine, “Amicus curiae in international investment arbitration: the implications of an increase in third-party participation,” Berkeley Journal of International Law 29, 217.

[2] Tomoko Ishikawa, “Third Party Participation in Investment Treaty Arbitration,” The International Comparative Law Quarterly 59/2 (April 2010), pp. 373-412.

[3] Benjamin Miller, Jennifer Liu, Ramin Wright, Jenny Yoo, “Guide for Potential Amici in International Investment Arbitration,” Center for International Environmental Law (January 2014), 11.

How to participate in different fora

The rules for participation vary slightly across investment arbitration fora. This section discusses the difference between the International Centre for the Settlement of Investment Disputes (ICSID) and the United Nations Commission on International Trade Law (UNCITRAL). The rules governing investment arbitration in Bilateral Investment Treaties (BITs) can also vary, but often follow the procedures of the two international organizations noted above.

For ICSID disputes, amicus curiae submissions are accepted after both parties to the dispute are first consulted by the tribunal and serve to provide “a perspective different from that of the parties, via the submission of a written brief.”[1] The procedural rule that governs amicus curiae submissions is outlined in Arbitration Rule 37(2). It states that for a request to submit an amicus curiae to be granted, the following items are considered:

  • whether the submission would assist the Tribunal by providing a perspective different from the disputing parties;
  • whether the submission would address a matter within the scope of the dispute, and
  • whether the non–disputing party has a significant interest in the proceeding.[2]

For UNCITRAL disputes, the rules governing amicus curiae submissions are detailed in Article 4 and 5 of the UNCITRAL Arbitration Rules. A written request must be made to the arbitral tribunal outlining information on the non-disputing party and its interest in the dispute (See Article 4(2) a-e). Based on this request, the tribunal then decides whether or not to admit an amicus curiae submission. The rules state:

In determining whether to allow such a submission, the arbitral tribunal shall take into consideration, among other factors it determines to be relevant:

  • Whether the third person has a significant interest in the arbitral proceedings; and
  • The extent to which the submission would assist the arbitral tribunal in the determination of a factual or legal issue related to the arbitral proceedings by bringing a perspective, particular knowledge or insight that is different from that of the disputing parties.[3]

It is important to note that in making this decision, the tribunal also seeks to “ensure that any submission does not disrupt or unduly burden the arbitral proceedings, or unfairly prejudice any disputing party.”[4] This is mainly to ensure that the costs of arbitration are kept reasonable, as disputes can take a number of years to resolve, and any additional burden could stress the capacity of the parties to the dispute, particularly for developing countries.         

Overall, the guidelines for submitting amicus curiae briefs to investment tribunals is fairly straightforward and vary in minor ways. Generally speaking, however, the practice of accepting amicus curiae submissions appears rather permissive. For instance, in a recent NAFTA (North American Free Trade Agreement) Chapter 11 case, Eli Lilly and Company v. Canada (ICSID Case No. UNCT/14/2), a number of legal scholars specializing in intellectual property, and other organizations, successfully submitted amicus curiae briefs. This is but one indication that amici curiae participation is open to a variety of interests.


[1] ICSID, “Non-Disputing Party Submission- ICSID Convention Arbitration,” accessed July 7, 2016,

[2] ICSID Convention Arbitration Rules, Arbitration Rule 37(2).

[3] UNCITRAL Arbitration Rules, Article 4(3).

[4] UNCITRAL Arbitration Rules, Article 4(5).


Inu Manak, Ph.D. Candidate, Georgetown University Department of Government

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