On June 8, Ratko Mladić, the Bosnian Serb commander, lost his appeal before the United Nations International Residual Mechanism for Criminal Tribunals (Mechanism) Appeals Chamber in The Hague, Netherlands. The Appeals Chamber in Prosecutor v. Ratko Mladić affirmed Mladić’s convictions for genocide, war crimes, and crimes against humanity perpetrated during the war in Bosnia between 1992 and 1995, as well as his sentence of life imprisonment. The judgment brings to a close the last major case initiated by the U.N. International Criminal Tribunal for the Former Yugoslavia (ICTY), which was established in The Hague in 1993 to prosecute perpetrators of atrocity crimes in the Balkan region. The Mladić case thus offers an opportunity to assess not only the judgment itself, but also the ICTY’s legacy.

Substantively, the Mladić appeals judgment both affirms the Trial Chamber’s judgment and echoes the findings of Prosecutor v. Radovan Karadžić, the ICTY’s “sister case” against the former Bosnian Serb president, Radovan Karadžić. That case was based on the same indictment and it is the case on which I worked in Chambers from 2011 to 2013. The key to understanding the Mladić opinion—and most ICTY legacy cases—is to think primarily through joint criminal enterprise (JCE), a mode of group criminal liability established early in the ICTY’s history. JCE resembles the American criminal law concept of conspiracy, however the actus reus (or criminal act requirement) differs: American conspiracy, an inchoate offense, typically requires a slight “overt act,” whereas JCE requires that a group member actually perpetrate a criminal act. In the Mladić indictment, prosecutors alleged (1) an “overarching JCE” in which the Bosnian Serbs between 1992 and 1995 tried to remove Croats/Muslims permanently from Bosnia, plus (2–4) three “smaller” JCEs (spreading terror in Sarajevo, elimination of the Bosnian Muslims in Srebrenica, and taking U.N. personnel hostage).

The Mechanism affirmed the ICTY Trial Chamber’s 2017 finding that Mladić, as commander of the Main Staff of the Bosnian Serb army between 1992 and 1995, was part of all JCEs and thus criminally responsible for genocide, war crimes, and crimes against humanity. Much of this was expected: as an evidentiary matter, Mladić was a more straightforward case than Karadžić, given that more video and other evidence existed of Mladić “on the ground” than of President Karadžić. The notable exception was Count 1: the Mechanism affirmed the Trial Chamber’s acquittal on that count, which had alleged that he perpetrated genocide in Bosnian municipalities outside of Srebrenica. In other words, the Appeals Chamber affirmed the Trial Chamber’s finding that the prosecution failed to prove the specific genocidal intent to destroy a substantial part of the Bosnian Muslim population. The prosecution appealed on this ground (again) and lost (again)—just as it did in Karadžić. The Appeals Chamber also affirmed the Trial Chamber’s sentence of life imprisonment, the maximum sentence available under the ICTY statute.

How should we contextualize Mladić within modern international criminal law? On the one hand, Mladić powerfully exemplifies the ICTY’s positive, transformative legacy. First, the ICTY brought to justice the infamous “Butcher of Bosnia,” among the most notorious figures in the former Yugoslavian wars and one who evaded capture until arrest in 2011. The central goal of international criminal law is to achieve justice for victims, and this case certainly did that—including for the families living on in the wake of the Srebrenica massacre. Second, the conviction reaffirms the Tribunal’s improbable success: established in 1993 as a modern incarnation of the post-World-War-II Nuremberg International Military Tribunal, it slowly built institutional legitimacy and international authority to the point where Mladić’s arrest evolved into a geopolitical and moral imperative, even removing an obstacle to Serbia’s push for European Union membership. And third, most broadly, the ICTY stands as a catalyzing “first mover” tribunal in a modern era of international criminal accountability that aspires to an end to impunity for “the most serious crimes of concern to the international community.”

But Mladić reminds us—almost 30 years after the ICTY’s establishment—both of the limits of the “Hague tribunal” model of international criminal accountability and the proliferation of diverse modes of international criminal accountability today. Mladić is one of the last judgments of the “Hague tribunal” institutional model—wherein the ICTY and its sister tribunal, the U.N. International Criminal Tribunal for Rwanda, were established and fully funded by the U.N. Security Council and international community. But ongoing challenges with this institutional arrangement—including their high cost and flagging perceptions of legitimacy in the Balkan region—led to the successive wave of “hybrid” tribunals. Such tribunals featured a mix of domestic and international judges in or near the location of the atrocity crimes, as in the case of the Extraordinary Chambers in the Courts of Cambodia, founded in 2003. A third model is the permanent International Criminal Court (ICC), created by a multilateral treaty but facing the central challenges of State party ratification and enforcement. Other tribunals, such as the Special Tribunal for Lebanon (established 2009) or the Kosovo Specialist Chambers & Specialist Prosecutor’s Office (established 2017), represent variations on such models.

Such international enforcement models complement and contrast with another major front in contemporary criminal law enforcement: the ongoing empowerment of domestic jurisdictions to investigate and prosecute international and transnational crime. As is well known, the ICC functions on a foundation of deferential complementarity, wherein it will only prosecute if a country is unwilling or unable to prosecute. Contemporary international investigative mechanisms share in this deference, building an evidentiary record for atrocity crimes in Myanmar and Syria, leaving formal prosecution to a future national, regional, or international actors. Meanwhile, national jurisdictions are continuing to reach abroad, asserting jurisdiction over not only atrocity crimes—as was the case recently, for example, in the February 2021 German prosecution of a Syrian secret police officer for crimes against humanity—but also for a variety of extraterritorial offenses under the “long arm” of U.S. foreign affairs prosecutions, which may implicate both defendant rights and foreign relations more broadly.

In sum, Mladić achieves the central, noble aim of international criminal law: ending impunity for those who have perpetrated the most serious global crimes. And—owing to both the ICTY’s successes and challenges—the case exemplifies the Hague tribunals as modern catalysts in the dynamic context of international and transnational criminal law enforcement.

Image: Bosnian families follow the final verdict hearing of the former Bosnian Serb general Ratko Mladic also known as the “Butcher of Bosnia” in the ethnic cleansing case by the International Criminal Tribunal, from a screen at Srebrenica Genocide Memorial in Potocari in Srebrenica, Bosnia And Herzegovina on June 08, 2021. Photo by Elman Omic/Anadolu Agency via Getty Images