The hearings for the Climate Change Advisory Opinion at the International Court of Justice (ICJ or Court) are fast approaching, scheduled to start on 2 December, with participation from over 100 States and international organisations. However, a statement released by the ICJ on 26 November revealed that the judges held a meeting with members of the Intergovernmental Panel on Climate Change (IPCC) ‘to enhance the Court’s understanding of the key scientific findings which the IPCC has delivered through its periodic assessment reports covering the scientific basis, impacts and future risks of climate change, and options for adaptation and mitigation’.
This approach by the ICJ is intriguing for several reasons. Notably, the Court has not specified the procedural rule under which it convened with IPCC members, raising concerns about whether the ICJ is overstepping its adjudicative role to act as an independent fact-finder. This shift prompts important questions about the Court’s function and the procedural boundaries of advisory opinions.
This post will examine the possible legal and procedural grounds for the ICJ’s actions and assess whether the Court risks overstepping its role. It will also explore whether such engagements with experts fantômes may blur the lines of fact-finding and whether they are adequate.
What is the legal basis of this meeting?
First, under Article 30(2) of the Statute of the ICJ, the Court may appoint an independent assessor to sit on the panel of judges without voting rights, thus closer to a judge than a court-appointed expert. Such an ex-curia expert can provide valuable insights into complex technical or scientific matters beyond the expertise of the judges. Surprisingly, the Court has never utilised this procedure. The only notable reference to it appears in the Separate Opinion of Judge Petrén in the Western Sahara Advisory Opinion (p.13), where he expressed regret that the Court did not appoint an assessor to provide expertise on Islamic law and the history of northern Africa.
In the context of the Climate Change Advisory Opinion, the appointment of an assessor or multiple assessors under Article 30(2) could have been beneficial, as it would have allowed the judges to access specialised scientific expertise on climate change. However, the failure to utilise this provision may be due to concerns over procedural fairness. Once appointed, an assessor’s opinion and evidence are not subject to comment by the parties involved in the advisory opinion, potentially influencing the proceedings in a manner perceived as “secretive”, as described by Lucas Carlos Lima. Another reason why the ICJ might have refrained from appointing an assessor is the inherent complexity and variability of scientific interpretations. Climate science can be explained in multiple ways, with no universally accepted approach. For instance, should the focus be on the science of attribution, the discount rates applied to future climate impacts, or the causes of climate change itself? This diversity in perspectives may have further complicated the appointment of an assessor.
The ICJ’s recent meeting with members of the IPCC, without citing any procedural basis, adds another layer of complexity and doubt to these proceedings. Critics such as Chester Brown (p. 113) argue that this approach lacks transparency, as it bypasses established mechanisms like Article 30(2) and leaves questions about accountability unanswered.
That said, roles akin to assessors have been successfully employed in other contexts. For instance, in the ad hoc tribunals of the PCA, such as Croatia v Slovenia or the South China Sea Arbitration, such roles facilitated the resolution of complex technical issues. These examples demonstrate that similar mechanisms can enhance judicial processes without compromising transparency, provided they are carefully implemented.
Second, under Article 50 of the Statute of the ICJ, the Court may entrust individuals, organisations, or other bodies with expert-like functions to aid in understanding the technical or scientific complexities of a case. Article 67(1) of the Rules of the ICJ specifically governs the procedure for selecting and appointing experts. The Court refrained from formally appointing any experts under this procedure; hence, the listed IPCC members are not Court-appointed experts.
In practice, however, the Court’s use of Article 50 to appoint experts has been scarce. Notable instances include the Factory of Chorzów (Indemnity), Corfu Channel case (naval experts), and the Caribbean Sea Delimitation case. A significant question arises as to whether Article 50 can be applied in advisory proceedings, given that these examples all stem from contentious cases.
This issue was raised in the Separate Opinion of Judge de Castro (p. 130) in the Western Sahara Advisory Opinion where he argued against the use of Article 50 experts in advisory proceedings. However, as Tams and Devenay (p. 1439) contend, Article 50 should not be applied restrictively. The Court clearly has the discretion to extend provisions applicable to contentious cases to advisory proceedings under Article 68 of the Statute and Article 102(2) of the Rules of the Court.
Finally, it cannot be argued that the Court is exercising its powers under Article 69 of its Rules, which enables a “public international organization” to provide information on the matter before the Court. The ICJ’s press statement explicitly refers to a group of “past and present authors of the reports of the IPCC” rather than a public international organization, meaning that Article 69 is not applicable in this case. Two issues arise: first, how were these listed IPCC members selected, and who was chosen to meet with the ICJ judges? Without adherence to due process, the selection may be perceived as biased. Similarly, suppose there was a meeting with the ICJ judges. Why did the IPCC, or even the World Meteorological Organization, not submit written statements to the ICJ, which could have been done under Article 69 of its Rules? There is, therefore, no clear legal basis applicable in this instance.
Informal expert advisers?
In the absence of a legal basis for this meeting, it raises the question of whether the ICJ is engaging in independent fact-finding or informally leveraging the expertise of external specialists, so-called “experts fantômes”. The ICJ’s past practice demonstrates its ability to rely on information concerning technical or scientific facts in other proceedings, both judicial and quasi-judicial, such as in the Bosnian Genocide case. However, this must be distinguished from the current meeting and consultation between the ICJ and members of the IPCC. In the Bosnian Genocide case, the ICJ did not consult the ICTY but rather relied on evidence that was deemed “highly persuasive” (para. 223 of the judgment), thereby crossing the boundary into fact-finding.
Of course, relying on other fact-finding bodies is often desirable to ensure the Court reaches a well-reasoned decision. The issue becomes more problematic when the Court engages in independent fact-finding, effectively outsourcing this role. Independent, ad hoc fact-finding risks producing inaccuracies, especially when conducted without the support of an ex-curia assessor or a court-appointed scientific expert who could advise the judges throughout the advisory proceedings.
While it is commendable that the judges are addressing their limitations in scientific expertise, the lack of a clear procedural basis for their actions raises concerns about transparency, due process, and adherence to the rule of law. Sir Robert Jennings (p. 416) commented (seems with approval) that the ICJ has frequently resorted to:
cartographers, hydrographers, geographers or linguists, and even specialised legal experts to assist in the understanding of the issues in a case before it, and it has not, on the whole, felt any need to make this public knowledge or even to apprise the parties.
Based on this, the ICJ’s invitation may be seen as a resort to informal experts fantômes (albeit publicly announced) rather than the formal appointment of an assessor, expert, or international organisation. This approach raises broader questions about the procedural implications of circumventing the Court’s Statute and Rules. In fact, this criticism was highlighted in the Joint Dissenting Opinion of Judges Al-Khasawneh and Simma in the Pulp Mills Case (para 14), in which the judges argued that such practices reflect poorly on the administration of cases and advisory opinions. Instead both argued that the court should appoint experts formally rather than get advice behind closed doors. Anna Riddell has further demonstrated in her extensively researched article that when the Court relies on experts fantômes, it often leads to uncertain factual propositions, thereby undermining the integrity of the proceedings. The use of experts fantômes effectively circumvents the opportunity for States to comment on the expert views.
Even though IPCC reports are approved line-by-line by States, the ICJ’s reliance on this informal consultation process arguably lacks the openness expected of judicial proceedings. Interestingly, the International Tribunal for the Law of the Sea (ITLOS), in its Climate Change Advisory Opinion, did not employ any experts—formal or informal—making the ICJ’s decision to do so even more notable.
Uneasily positive about the Court’s approach?
In summary, the use of experts fantômes can be criticised for its lack of transparency in due process and the potential for significant issues, such as inaccuracies in the facts or science relied upon. However, it is nonetheless commendable that ICJ judges are making efforts to engage with climate science in preparation for the oral hearings, but this should not be done at the expense of general principles of international procedural law such as transparency, due process and procedural fairness.
Looking ahead, as Judge Yusuf stated in his Declaration in Pulps Mills (para 14), the Court should consider adopting a more systematic strategy for handling complex evidence by using the procedures outlined in the ICJ Statute and the Rules of Court regarding the methods for obtaining and examining evidence. This would reduce reliance on sui generis experts fantômes and enhance both transparency and procedural integrity.
