A Quiet Confusion: The ICJ’s Application of Amended Rules to Pending Cases

[Brian McGarry is Assistant Professor of Public International Law at Leiden University]

The just-concluded hearings in The Gambia v. Myanmar mark the culmination of a long campaign that expanded the reach of public interest litigation, while foreshadowing the popularization of third-State intervention in ICJ cases. All of this has received more than its share of attention, including the Court’s admission of 11 intervening States in this case. By contrast, one hears not a word about its decision to silence those States through the extraordinary application of 2024 Rules of Court to a case filed in 2019.

This recent amendment to the ICJ Rules reflects the first time the Court has modified its intervention procedure in nearly a half-century. It introduced two distinct changes to the procedure for intervention under Article 63 of the Statute: an earlier deadline for declaring intervention; and the removal of a longstanding entitlement for interveners to raise their views in open court.

This post does not ask whether the latter change is consistent with Article 63’s proviso that “the construction given by the judgment will be equally binding upon” the intervener. It does not address the ICJ Rules’ continued recognition of an entitlement to make oral submissions under Article 62 of the Statute, or how this confirms that these mechanisms serve different interests. Nor does it call into question the ICJ’s finding in The Gambia v. Myanmar that the interveners’ written pleadings—which the applicant framed as “speak[ing] with one voice” (p. 24)—had “sufficiently informed” the Court in this instance (p. 2).

Rather, I will pose two questions, and answer them in the affirmative: has the Court strained the limits of its authority by applying amended Rules to a pending case; and has this quietly given rise to both acceptance and resistance in State practice?

PCIJ Practice

The retroactive application of the Rules of Court was first considered 100 years ago. As the PCIJ began amending its Rules in 1926, the judges agreed that great caution was required when enacting “substantial” amendments, as distinguished from those which could be characterized as matters of form or the internal organization of the Court. They maintained this distinction even as President Huber and others foresaw its blurriness on matters ranging from judges ad hoc to diplomatic representation, which illustrated that “one never knew exactly at what point a correction of form really became a substantial correction” (pp. 25, 142, 304). This caution dictated that the Court should not amend any rule “which, in reality, concerned the rights of States, without having heard the views of the parties” (p. 20).

Due to these concerns, many judges were particularly reluctant to apply amended Rules to pending cases. Concurring with Judges Adatci, Fromageot, and Schücking at the outset of deliberations on the 1936 Rules, President Hurst considered that a case having been recently filed before the Court was “a good reason for postponing the coming into force of any amendments […] until after the examination of the said case” (p. 11). When asked by Judge Nagaoka in the final hour of that two-year project “whether it was correct to apply the new Rules to cases which had been submitted under the old Rules”, however, the President was by then prepared to accept this because the new Rules “were not substantial amendments and generally speaking simply codified the Court’s earlier practice” (p. 739). The Court thus justified its application of new Rules to subsequent phases of pending cases because the relevant change to the Rules—preliminary objection deadlines—solely concerned “the organization and internal administration of the Court”, and did not limit the rights of States (Losinger, p. 22;Pajzs‚ Czáky‚ Esterházy, p. 8).

Historical ICJ Practice

The inaugural ICJ Rules of Court essentially repeated the PCIJ Rules, in accordance with the “chain of continuity” envisaged in San Francisco. The Rules remained unchanged until 1972, when the Court modified them with the caveat that pending cases will “continue to be governed by the Rules in force before that date” (p. 195). Consequently, the bench continued to apply the old Rules to all phases of such cases. As recalled by Judge Jiménez de Aréchaga (a principal drafter of the 1972 Rules), “[t]he reason for this is that since the old Rules apply to the proceedings on the merits of a case submitted before September 1, 1972, they should a fortiori apply to any incidental proceedings arising in that case, whatever the date of the commencement of such incidental proceedings” (p. 21). The old Rules would thus apply to all interventions, counter-claims, preliminary objections, and provisional measures in pending cases (as seen in Fisheries Jurisdiction, p. 304).

As Judge Lachs observed (p. 50), this logic of ex abundanti cautela was maintained (p. 3) when the Rules were revised in 1978 (p. 112). The Court thus continued to apply the previous Rules in its correspondence with the parties in Aegean Sea (p. 592), and reiterated this in its final judgment (para. 11). While its 1978 overhaul led to the creation of a standing Rules Committee charged with “ongoing review” of the Court’s procedures, the Court did not undertake any further modifications until 2001, when it amended procedures for preliminary objections and counter-claims. In line with its well-established approach, the Court disregarded these Rules in all phases of cases instituted before 2001 (Armed Activities,para. 27; Croatia v. Serbia, p. 611; Diallo, para. 5).

Recent ICJ Practice

In 2005, the Court adopted and stated in the preamble of its Rules a new promulgation procedure for amendments which, on the surface, appeared to be purely cosmetic. From this point forward, the Court would indicate entry-into-force dates of amendments in footnotes, rather than a sequence of citations in an enacting clause. Yet in so doing, it would also provide “a note of any temporal reservations relating to their applicability”, including “whether the application of the amended rule is limited to cases instituted after the date of entry into force of the amendment”. It thus appeared that the Court had flipped a longstanding presumption against the retroactive application of new Rules.

This has not exactly surfaced in the Court’s subsequent practice, however. While it has applied a number of Rules to cases pending before their adoption, in all but one instance these Rules concerned matters such as enabling hybrid hearings in response to COVID-19, thus allowing the Court “to continue to discharge its judicial functions” (Qatar v. UAE, p. 12). As President Donoghue observed, such amendments simply reflect a need for the Court to adapt its procedural reality to the external environment (p. 2). They may thus be regarded as “insubstantial” according to the PCIJ’s reasoning, especially as they preserve States’ voices in the proceedings (rather than restricting their participatory rights). The retroactive application of such Rules does not raise eyebrows.

Until now, the sole outlier has been Guyana v. Venezuela, a case characterized by extremely novel procedures befitting a respondent that chose to participate (and raise preliminary objections) after the Court had rendered a judgment affirming its jurisdiction. Yet what truly distinguishes this case in the present context is that the applicant (pp. 13, 30) and respondent (para. 12), in the course of the proceedings, expressly consented to the application of amendments concerning preliminary objections that had entered into force while the case was pending.

Despite the Court’s indication in the post-2005 preamble to the Rules that it will specify instances where the amended rule is limited to cases instituted after its date of entry into force, the only temporal reference in the present Rules of Court concerns its 2023 amendment, which construes the text of the Rules and other internal documents as gender-inclusive—and which the Court expressly applied with immediate effect. There is thus little clarity in the 2005 development, and even less basis to argue that it had altered the prior practice, as the use of gender-inclusive terms clearly concerns the Court’s organisation and internal administration (rather than the rights of States appearing before it).

The Presumption of Non-Retroactivity

We may thus cautiously identify only two exceptions in the Court’s longstanding practice (and, one could argue, in the general principles governing international judicial procedure) to the non-retroactivity of amendments: first, where the modification may be characterized as “insubstantial”; and second, where the parties explicitly agree to the application of an amended rule to a pending case.

Applying the first exception, the dubious question in the present context is whether the Court’s 2024 amendments resemble any previous examples of clearly insubstantial Rules. While the PCIJ’s practice suggests that the amendment concerning deadlines for filing incidental proceedings may well be characterized as insubstantial, it is difficult to assert the same regarding its removal of an intervener’s entitlement to make oral submissions. In fact, the importance of this right has been clear enough since the deliberations regarding the PCIJ Rules (pp. 142, 311). It is yet more challenging to frame as insubstantial an amendment which, rather than codify the Court’s earlier practice, explicitly curtails entitlements that have held firm for a century.

Moreover, it is doubtful that intervention should be distinguished in this regard simply because this process involves non-parties joining a case after it is instituted. It should be recalled that, particularly in our present era of strategic inter-State litigation and coordination of mass intervention, sudden changes in these Rules may frustrate the expectations of a party as much as an intervener. More fundamentally, the Court has long held that “every intervention is incidental to the proceedings in a case” (Haya de la Torre, para. 76). It thus remains unclear as to why any such distinction could justify applying newly amended Rules to proceedings on the merits of a seven-year case.

Regarding the second exception to the non-retroactivity of the Rules, we have seen that prior to the present hearings, the ICJ had applied amended Rules to a pending case on only one notable occasion, and solely with the parties’ expressly provided consent. In Guyana v. Venezuela, the respondent explicitly invoked the Court’s contemporaneous amendments, and the applicant confirmed its acceptance in open court. This supports the view that such consent should be clear and explicit, rather than assumed through tacit silence.

Judicial practice on this point—including in the same context as the Court’s 2024 amendments—has given States good reason to raise their voices today.Indeed, over 40 years ago, an intervention request provided a rare but critical reminder that the ICJ’s rulemaking powers are not immune to challenge. Following Italy’s argument in Continental Shelf that the Rules of Court had improperly introduced a condition limiting its statutory right to intervene (para. 18), the Court in Gulf of Fonseca interpreted the relevant Rule in a way that effectively neutered it (para. 100).

This demonstrates vividly that when States understand the Rules of Court, they may seize the opportunity to cautiously protest—an opportunity which is jeopardised when new Rules are assumed to apply to cases already in progress. Since the Court’s 2024 amendments, intervention declarations filed in each of its pending Genocide Convention cases appear to have reserved a right to this resistance by conspicuously avoiding reference to the new Rules (e.g., Belize, Bolivia, Brazil, Chile, Estonia, Ireland, Latvia, Lithuania, Luxembourg, Spain, and Sweden). Still other declarations filed during this period invoke both the old and new Rules (including Bulgaria (paras. 2, 17), DRC (paras. 2, 6), Denmark (paras. 2, 14), Poland (paras. 2, 22), and a joint intervention submitted by Austria, Czechia, Finland, and Slovenia (paras. 2, 5)), which illustrates the current potential for confusion.

Concluding Observation

While the Court enjoys broad discretion in its rulemaking authority under the Statute, this is not an entirely blank cheque, as Kolb (p. 101) and Thirlway (p. 595) have emphasized. In particular, it should be construed in light of common procedural principles reflected in the life of the Court—principles which may have more bearing on its judicial function than the pursuit of judicial economy. The ICJ’s recent approach of surgically amending (and now retroactively applying) specific Rules cautions that the faster it moves, the more attention it requires from States and counsel. In the Hippocratic view of Judges Anzilotti and Urrutia nearly a century ago: “If there was any doubt, it would be better to leave things as they were” (p. 21).