The Concept of International Organization in the practice of the International Court of Justice

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On 14 June 2023, the ICJ authorized the International Union for Conservation of Nature (“IUCN”) to participate in the proceedings on the Advisory Opinion on the Obligations of States in respect of Climate Change (“climate change AO”). As is usual in such requests by international organizations, no reasoning was given by the Court for its decision. However, due to certain specificities of the IUCN, this authorization could imply an expansion of the concept of international organizations (IOs) under Article 66 of the Statute of the Court, as well as under international law.

The criteria of Article 66 and the IUCN

Indeed, Article 66, which the Court cited to ground its decision, authorizes any “international organization considered by the Court, or, should it not be sitting, by the President, as likely to be able to furnish information on the question” to participate in AO proceedings. In other words, Article 66 institutes two criteria for participation by non-State actors: (i) the actor must be an international organization and (ii) the actor must be able to furnish information relevant to the AO proceedings.

The second element of the criteria is easily met by the IUCN. Article 2 of the IUCN Statutes (the constituent instrument of the organization) establishes that IUCN’s objectives are, inter alia, to disseminate information about research related to the conservation of nature and natural resources, to prepare statements on conservation, and to take other appropriate action to promote the conservation of nature and natural resources. Engaging with the ICJ and with other States and IOs in the climate change AO would fall neatly within the functions the IUCN was created to fulfil. The decision of the Court does not innovate in relation to this criteria.

What is interesting from the point of view of the law of international organizations is the decision of the Court to consider the IUCN as an international organization. That is so mainly due to two aspects: the membership of the IUCN and the nature of its constituent instrument.

Regarding membership, the key difference between the IUCN and more typical international organizations is that it is comprised not only of States and other IOs. As per its website,  the IUCN has more than 1,400 member organizations, which include States, governmental agencies, NGOs, indigenous peoples’ organizations, academic institutions, and business associations. Indeed, State and government agency members make up “approximately 14% of IUCN’s Membership”. This is further confirmed by Article 3 of the IUCN Statute, which divides members into four different categories. States and IOs fall under Category A, whereas Categories B, C and D are comprised of NGOs, indigenous peoples’ organizations and affiliations, respectively. Here, it is worth noting that Article 69(4) of Rules of the Court understands a “public international organization” to denote an “international organization of States”; however, the term used in Article 66 of the Statute is “international organization”, and Article 69(4) of the Rules of the Court does limit the concept to the “foregoing paragraph”. It is thus not incompatible for an organization like the IUCN to be considered an international organization under Article 66.

The IUCN is also unlike most other international organizations due to it not having been created by an international instrument or treaty. Rather, as pointed out by a commentator, Article 1 of the IUCN Statutes clarifies that it was “constituted in accordance with Article 60 of the Swiss Civil Code as an international association of governmental and non-governmental members”. The relevant Article of the Swiss Civil Code clarifies the circumstances in which associations for a “political, religious, scientific, cultural, charitable, social or other non-commercial purpose” acquire legal personality, as well as puts forth certain requirements for the articles of association of said organization.

While it is common for international organizations to also have domestic legal personality (see e.g., Article 104, UN Charter), their constituent instruments normally either afford them international legal personality or are silent as to their precise legal personality. Nonetheless, the Court’s dictum in Reparations for Injuries regarding implicit legal personality (“[…] the rights and duties of an entity such as the [United Nations] must depend upon its purposes and functions as specified or implied in its constituent documents and developed in practice”) does suggest that an organization whose functions include engaging in international fora on environmental matters, and that has engaged in other proceedings before international courts and tribunals, should be considered to have international legal personality.

Practice Direction XII

That being said, the recognition of a not purely inter-governmental organization as an IO within the meaning of Article 66 by the Court is still progressive. Departing from both the language of Article 66 of the Statute and Article 69 of the Rules of the Court, Practice Direction XII of the Court introduces, and distinguishes between, the concepts of “intergovernmental organizations” and “international non-governmental organizations”. It authorizes the latter to submit written statements or documents in an advisory opinion case on its own initiative, with the caveat that such submission “is not to be considered as part of the case file”, largely treating it “in the same manner as publications in the public domain”.

It is worth noting that the Court has not understood the IUCN to be an international non-governmental organization. This is clear from the language of the press release (which, albeit unofficial, is the only available document on the decision of the Court): “The IUCN may therefore present a written statement on those questions, and written comments on any written statements made by States or other organizations” (emphasis added). The procedure of commenting on written and oral statements is reserved for States and intergovernmental organizations, as per paragraph 3 of Practice Direction XII.

The ambivalent practice of the ICJ

While the decision of the Court seems to be legally sound, the question remains as to whether it is in any way novel. The answer is both yes and no: there has been one instance in the past of an organization that was not purely intergovernmental being authorized to participate in proceedings before the Court, the International League of the Rights of Man (“International League”). However, the position of the Court with regard to the status of this organization has been ambivalent.

First, in the Asylum (Colombia/Peru) case (p. 228), the Court denied the International League’s request to participate under Article 34 (which uses the terminology public international organization) as it understood that the International League “cannot be characterized as a public international organization”. On the same day, the Court authorized the same International League to submit a “written statement of the information likely to assist Court [sic] in its examination of Iegal questions put to it in Assembly [sic] request concerning South-West Africa” (p. 327) – however, the International League failed to submit its written statement within the time-limits, and the document submitted lacked proper signature. In subsequent correspondence with the International League, the Court’s Deputy-Registrar explained that “the Court did not contemplate resorting further to your League in present case [sic]” (p. 346). Two decades later, in the Namibia AO, the International League again sought permission to participate in the proceedings, however, it was not authorized to do so. No further reason was given by the Court (p. 672).

Although Practice Direction XII would only be promulgated many decades after, one could argue that, by authorizing the International League to submit a written statement in the context of an AO and on the same day denying its request to participate in an inter-State dispute due to it not being a public international organization, the Court understood the International League to be akin to an “international non-governmental organization” – and not an intergovernmental organization. As such, the case of the IUCN could be the first time that a not purely inter-governmental organization was considered to be an international organization under Article 66 and authorized to participate in advisory proceedings.


While wholly consistent with its case law, Statute and internal rules and directives, the decision authorizing the participation of the IUCN represents a novel and important step in the Court’s jurisprudence. By authorizing an international organization whose membership is not composed exclusively of States and other IOs to participate in advisory proceedings under Article 66, the Court has signaled that, in line with its position in Reparations for Injuries, what characterizes an international organization as such has more to do with its functions and practice than with stale concepts of international legal personality (whose practical relevance is indeed questionable).

Nonetheless, the lack of an order presenting the legal reasoning behind the Court’s decision limits the relevance of this decision for other organizations seeking to participate in this and other advisory proceedings – especially as the case of the International League does suggest some degree of arbitrariness in such decisions. This, in turn, could be mitigated by clearer standards, construed and clarified through reasoned decisions, regarding what constitutes an international organization and what makes it likely to be authorized to furnish relevant information under Article 66.

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