Symposium on The Principle of ne bis in idem in International Criminal Law: Inter-jurisdictional Rules in the Rome Statute

[Megumi Ochi is associate professor at the Graduate School of International Relations, Ritsumeikan University, Kyoto. The Premises of International Criminal Procedure: Identifying the Principles in International Collaboration (Springer, 2024) is the English translation of her second monograph.]

I am honoured to be invited to this book symposium on this outstanding monograph written by my friend, Gaiane, on a topic that has interested me since my graduate school years. While I am not yet ready to publish the English translation of my first Japanese monograph on ne bis in idem in international criminal justice, Gaiane’s work is extremely encouraging and meaningful. The issue of ne bis in idem is highly complex, as indicated below, but Gaiane’s straightforward explanation and explicit articulation of her opinions will assist me—and future scholars—in continuing to engage with this debatable and evolving topic.

The topic of ne bis in idem is particularly compelling because it involves both cognitive questions and policy considerations. It is a principle that prohibits repeated trials, but determining what constitutes a “repeat” requires philosophical reflection: “What does it mean to be the same?” and “What does it mean to ‘repeat’?” Moreover, in international or inter-jurisdictional settings, the ne bis in idem principle is tasked with functioning as a kind of jurisdictional gatekeeper. The ne bis in idem rules of the ICC are designed to strike a balance between compliance with internationally recognized human rights and respect for state jurisdiction. Gaiane accurately frames this by stating, “’The ne bis in idem principle’ embodied in Article 20 of the Rome Statute is a complex and idiosyncratic formula.” And “This formula consists of a set of rules which seek to realize the same aim of protecting the person’s interest in not being tried twice for the same matter while also respecting a fundamental aspect of the legal system in which they operate: the complementary nature of the ICC’s jurisdiction.” (p. 159)

The topic I was assigned for this book symposium is limited to “due process and complementarity.” However, these two concepts are central to Gaiane’s discussion of the main topic and addressing them in the abstract would require another opportunity. For the purposes of this symposium, therefore, I will discuss these issues with a specific focus on the “ordinary crimes exception.” While the ne bis in idem rules in the Rome Statute are designed to balance due process and complementarity, the most delicate issue concerns how to address cases involving prior proceedings or retrials for “ordinary crimes” in domestic courts. In what follows, I will quote and examine Gaiane’s interpretation and evaluation of the relevant provisions on this issue.

In this review, I will use the terms “ordinary crimes” and “core crimes” for the sake of convenience, without offering detailed definitions of these concepts (For more discussion, see e.g. here or here).

“Downward” ne bis in idem in Article 20(2)

One of the biggest decisions for the drafters of the Rome Statute was whether to prioritize preserving room for States to exercise their jus puniendi—to try the same person for the same conduct for (ordinary) crimes other than those already tried by the ICC. Often, cases involving rebel groups are prosecuted as treason, and cases against former dictators are tried as internal insurrection. Sometimes, these domestic charges may be considered even more serious than core crimes. This balancing act is most clearly reflected in the specific formulation of the so-called “downward” ne bis in idem in Article 20(2), which stipulates: “No person shall be tried by another court for a crime referred to in article 5 for which that person has already been convicted or acquitted by the Court.” Thus, the Rome Statute allows a subsequent trial for the same conduct under different ordinary crime classifications.

Gaiane approaches the issue of the scope of Article 20(2) primarily from the perspective of “internationally recognized human rights.” She acknowledges that the “internationally recognized human rights” standard is itself controversial: “The varying content of the ne bis in idem guarantee in international human rights treaties makes it difficult to ascertain in this regard a single ‘internationally recognized human rights’ standard for the purposes of Article 21(3) of the Rome Statute.” (p. 107)

In addition, Gaiane explains this limitation as follows: “The role of international human rights law regarding the interpretation and application specifically of the scope of Article 20(2) is limited for essentially two reasons. Firstly, the content of the international human rights guarantee of ne bis in idem varies among the different international human rights instruments.” “Secondly, the application of the ne bis in idem guarantee in international human rights law is limited to a single jurisdiction.” (p. 108)

Gaiane concludes: “A ne bis in idem rule that bars repeat trial for the same offence rather than the same conduct is not incompatible with international human rights law.” (p. 109)

Admittedly, the inter-jurisdictional phase of criminal justice is one of the most unregulated areas of law. There is a legal lacuna during the extradition or surrender process. The suspect or accused may be placed in a legal vacuum during transfer. The current lack of international customary law on inter-jurisdictional ne bis in idem is problematic. The ICC mechanism could have served as a model for due process in such inter-jurisdictional criminal justice procedures. However, it seems that the ne bis in idem rule before the ICC was not designed with that goal in mind.

Gaiane, however, does not stop here. She argues for legitimate reasons to maintain protection: “Firstly, to permit the second trial in a domestic court of a person who has already endured a lengthy and complex trial before the ICC imposes a heavy burden on the individual”; “Secondly, after the conduct is tried and, where appropriate, punished by the ICC as an international crime within its jurisdiction, a subsequent domestic trial for the same conduct, albeit legally characterized as a different crime, adds little in terms of ensuring accountability for the very same conduct”; and “Thirdly, the interest of victims of the conduct tried by the ICC as an international crime within its jurisdiction can be vindicated through their participation in the proceedings before the Court and, in case of the accused’s conviction, through the reparations ordered by the Court.” (p. 109)

Although I agree with the first claim, I find the latter two less persuasive. First of all, both claims presuppose a conviction. It does not make sense to limit the discussion only to conviction scenarios unless we perceive this principle as prohibition of double “punishment”. If we consider the ne bis in idem principle a form of procedural protection, the level of protection should not vary based on the outcome of the trial. Second, there are cases that show that subsequent trials for the same conduct under different charges can add value. The Bagambiki case before the ICTR is one such example (see e.g. here). The accused was not tried for rape before the ICTR, despite credible allegations brought by women’s associations. After his acquittal, a local court retried him for rape based on substantially the same conduct.

“Upward” ne bis in idem in Article 20(3)

When it comes to “upward” ne bis in idem—that is, retrial by the ICC after a prior trial conducted by a state—the rules in the Rome Statute are more nuanced. It stipulates: “No person who has been tried by another court for conduct also proscribed under article 6, 7, 8 or 8 bis shall be tried by the Court with respect to the same conduct.” (This provision is complemented by two additional conditions regarding the quality of domestic procedures, but I will not discuss them here.)

Although the provision prohibits a subsequent trial for the same conduct, it limits its scope to conduct proscribed in the Rome Statute—that is, core crimes.

According to Gaiane, this means “the bar on repeat trial by the ICC applies even if the conduct is legally characterised as a different offence in the proceedings before the ICC.” (p. 127). This is a valuable comment, as some states adopt a “maximalist” approach to domestic implementation of the Rome Statute, such as the Philippines. In some states where core crimes are explicitly incorporated into domestic penal codes, the definitions may differ from those in the Rome Statute. For example, the definition of genocide in the Philippines includes “social or any other similar stable and permanent group” as a potential targeted group for genocide (Article 5 of the Philippine International Humanitarian Law Act) (see e.g. here or here). If the same conduct were tried in a Philippine court as genocide and then retried by the ICC as a crime against humanity, the ICC trial would be barred by Article 20(3).

Another notable remark is Gaiane’s observation that “a prior trial before another court for the ‘ordinary’ crime rather than an international crime does not constitute an exception to the ne bis in idem in Article 20(3).” This observation may pose challenges for some states in the future. States like Japan, which have adopted a “minimalist” approach to implementing the Rome Statute, anticipate that domestic trials for acts amounting to genocide or war crimes will proceed under general charges such as murder or rape. Japan does not criminalize genocide (as it is not a State Party to the Genocide Convention), nor has it incorporated war crimes into its domestic law (although it is party to all Geneva Conventions). Instead, Japan applies its Penal Code and certain special laws, such as those related to prisoners of war, to address such acts (see e.g. here or here). Several other states—particularly non-Member States of the Rome Statute—may follow similar paths.

While I have raised certain reservations regarding her normative arguments—particularly in relation to the added value of subsequent domestic trials and the scope of procedural protection beyond cases of conviction—I fully recognize the intellectual rigor and coherence of her approach. Indeed, these points of divergence are a testament to the richness of her work and its capacity to stimulate further debate.

In conclusion, Gaiane frames the balancing approach of Article 20 as follows: “Overall, these competing interests are the person’s interest in not being tried twice for the same matter; the state’s interest in the sovereign exercise of its criminal jurisdiction and characterising as it sees fit the conduct over which it is exercising its criminal jurisdiction; and the interests of the public, of the international community, and of victims in seeing accountability for crimes ensured.” (p. 158) The latter two perspectives must impact the provisions and add new views on understanding of this principle (that will be discussed in the other posts for this symposium).

This book not only deepens our understanding of the ne bis in idem principle but also raises broader questions about due process in inter-jurisdictional settings, legal fragmentation/pluralism, and the ICC system that was designed to be complementary. It will undoubtedly serve as a foundational reference for scholars, legal practitioners, and policymakers working at the intersection of international criminal procedure and human rights.