This article examines the legal and political significance of the enlarged partial agreement provision within the statute of the Special Tribunal for the Crime of Aggression against Ukraine. It argues that this mechanism not only enhances the tribunal’s operational feasibility but also elevates its institutional stature by enabling flexible international support, circumventing traditional diplomatic impasses, and reinforcing the normative architecture of international criminal law.
The establishment of a Special Tribunal for the Crime of Aggression against Ukraine by the Council of Europe represents a pivotal moment in the evolution of international criminal justice. Amid the limitations of existing institutions—particularly the jurisdictional constraints of the International Criminal Court (ICC)—the tribunal seeks to fill a critical accountability gap. Central to its design is the enlarged partial agreement provision, a procedural innovation that allows states to collaborate in pursuit of justice with this new tribunal.
Originating within the Council of Europe’s treaty practice, the enlarged partial agreement allows a subset of member states, along with non-member states, to jointly pursue specific objectives without requiring unanimous participation. This mechanism offers a pragmatic alternative to universal treaty ratification, enabling a coalition of willing States to act decisively in support of the tribunal.
There are essentially three types of agreements: a partial agreement between some member States of the Council of Europe; an enlarged partial agreement between some member States and one or more non-member state(s); and an enlarged agreement between all member States and one or more non-member state(s).
The provision’s utility lies in its capacity to bypass the procedural inertia that often paralyzes international legal initiatives. By permitting selective participation, the tribunal can mobilize legal, financial, and diplomatic resources more swiftly than traditional treaty-based institutions. This flexibility is particularly salient in politically charged contexts, where consensus is elusive and geopolitical interests diverge. Working with a management committee of interested States, nonparty states, and other institutions can shape and mold a support structure that will allow this new tribunal to do its work.
Moreover, the tribunal’s anchoring within the Council of Europe framework lends it administrative and institutional support, while the openness to non-member states ensures broader international engagement. This dual structure balances regional legitimacy with global inclusivity, making the tribunal both practical and politically viable.
Beyond operational concerns, the enlarged partial agreement enhances the tribunal’s normative stature. It signals a collective commitment to uphold the prohibition of aggression—a foundational principle of the UN Charter and customary international law. By targeting senior political and military leadership, the tribunal affirms the principle of individual criminal responsibility, challenging entrenched doctrines of immunity and impunity.
Furthermore, the tribunal complements the ICC’s mandate, reinforcing the architecture of international criminal law rather than fragmenting it. Its existence underscores the international community’s resolve to adapt legal mechanisms to evolving geopolitical realities, thereby strengthening the credibility of global justice norms.
The enlarged partial agreement provision is more than a procedural convenience—it is a strategic instrument that redefines how international justice can be pursued in the 21st century. By enabling flexible participation, circumventing diplomatic deadlock, and reinforcing core legal principles, it transforms the Special Tribunal from an aspirational concept into a realistic and dignified institution. In doing so, it reaffirms the international community’s capacity to respond to aggression not with paralysis, but with principled action.
David M. Crane is the founding chief prosecutor of the UN Special Court for Sierra Leone; the chair of a High Level Working Group supporting the Core Group of Nations in Creating the Special Tribunal on the Crime of Aggression against Ukraine; and the founder of the Global Accountability Network.
