Case Explained: Why a Convention on Crimes Against Humanity Matters – EJIL: Talk! – Legal Perspective

This is a post in our Joint Symposium on “Negotiating a Treaty on Crimes Against Humanity” run in partnership with Just Security. 

The international community stands at a pivotal moment in the evolution of international criminal law. While genocide and war crimes have long been codified in dedicated international treaties, crimes against humanity — arguably among the gravest violations of human dignity — still lack a comprehensive and binding global convention. This absence is not merely technical. It represents a normative gap with tangible consequences for accountability, prevention, and justice.

The ongoing efforts to draft a Convention on Crimes Against Humanity, initiated by the International Law Commission and now debated within the United Nations General Assembly’s Sixth Committee, offer a historic opportunity to close this gap. These efforts were at the heart of the seminar ‘Crimes Against Humanity – Advancing Towards a Dedicated International Convention’, held in Strasbourg on 26 September 2025, which brought together legal experts, diplomats, and practitioners committed to strengthening international justice.

Beyond a Technical Exercise

The drafting of a crimes against humanity convention is far more than a legal codification exercise. At its core, it is a collective reaffirmation of shared values — an acknowledgment that certain acts so fundamentally offend human dignity that they must be addressed through a universal legal framework.

Unlike genocide, which requires proof of specific intent to destroy a protected group, crimes against humanity encompass a broader range of systematic or widespread attacks directed against civilian populations. Murder, torture, enforced disappearance, sexual violence, and persecution on political, racial, national, ethnic, cultural, religious, or gender grounds all fall within this category. These crimes occur in times of war and peace alike, often exploiting gaps between international humanitarian law and international human rights law.

Despite their gravity, crimes against humanity currently rely on a fragmented legal architecture: customary international law, domestic legislation of uneven quality, and the jurisdiction of international or hybrid tribunals established on an ad hoc basis. A dedicated convention would provide clarity, consistency, and predictability — essential ingredients for effective prevention and prosecution.

From Draft Articles to Diplomatic Negotiation

The International Law Commission’s draft articles reflect years of careful legal analysis, drawing on jurisprudence from international criminal tribunals, state practice, and evolving human rights standards. Their transmission to the General Assembly marked the transition from expert-driven codification to state-led negotiation — a critical phase in which legal precision must be reconciled with political feasibility.

The discussions in Strasbourg highlighted both the promise and the complexity of this process. Debates on definitions, the scope of obligations, jurisdictional bases, and the relationship between international and domestic courts are not signs of weakness. On the contrary, they demonstrate that the treaty is being forged with seriousness and care.

One recurring theme is the need to strike a balance between clarity and inclusivity. A convention that is overly rigid risks becoming obsolete as international law evolves. One that is too vague, however, may fail to provide meaningful guidance to national authorities. The challenge lies in crafting provisions that are sufficiently precise to be operational, while flexible enough to accommodate future developments.

Prevention, Cooperation, and Accountability

A central strength of the proposed convention lies in its emphasis on prevention and interstate cooperation. Unlike existing instruments that focus primarily on punishment, the draft articles underscore the obligation of states to prevent crimes against humanity through legislative, administrative, and judicial measures.

Equally important are the provisions on mutual legal assistance, extradition, and aut dedere aut judicare — the principle that states must either prosecute alleged perpetrators found on their territory or extradite them to a jurisdiction willing and able to do so. In a world where perpetrators often cross borders with ease, such cooperation is indispensable.

By harmonising domestic criminal laws and procedures, the convention would reduce safe havens for perpetrators and enhance the prospects of justice for victims. It would also reinforce the principle that crimes against humanity are not the concern of a single state alone, but of the international community as a whole.

Reaffirming Humanity in an Age of Atrocities

As the international community moves from deliberation towards negotiation, it is essential to remember that the ultimate purpose of a crimes against humanity convention is not only legal. It is moral. It is about ensuring that the gravest crimes never go unanswered, and that those who endure them are never rendered invisible.

In this regard, the work of the Council of Europe offers important points of reference and synergy. International justice is at the core of its mandate, and several ongoing initiatives illustrate how regional efforts can complement global norm-building.

Parallel Efforts at the Council of Europe

First, the work towards the establishment of a Special Tribunal for the Crime of Aggression against Ukraine demonstrates how innovative legal mechanisms can be developed when existing frameworks prove insufficient. Although aggression differs in nature from crimes against humanity, both underscore the necessity of closing accountability gaps at the international level.

Second, the recent opening for signature of the Third Additional Protocol to the European Convention on Mutual Assistance in Criminal Matters highlights the importance of modernising cooperation tools. The 1959 Convention already extends well beyond Europe, with parties including Chile, Israel, Korea, and Mongolia. Strengthening such instruments directly supports the objectives of a future crimes against humanity convention.

Third, the Council of Europe Convention on the Protection of the Environment through Criminal Law which was opened for signature on 3 December 2025 marks a significant step in addressing environmental crime through binding international law. While the term ‘ecocide’ is not used explicitly, the substance of the convention covers acts that exacerbate the triple planetary crisis of climate change, pollution, and biodiversity loss. This initiative illustrates how international criminal law continues to evolve in response to emerging global threats.

Looking Ahead

The momentum behind a Convention on Crimes Against Humanity should not be underestimated. Yet momentum alone will not suffice. Sustained political commitment, inclusive dialogue, and legal craftsmanship will be required to transform draft articles into a widely ratified and effectively implemented treaty.

If successful, such a convention would not only fill a long-recognised gap in international law. It would send a powerful signal that the international community remains capable of learning from history, responding to contemporary challenges, and reaffirming the fundamental principle that some crimes concern all of humanity.

In doing so, it would honour the victims of past and present atrocities — and help ensure that future generations inherit a stronger, more coherent system of international justice.

This contribution expresses personal views of the author. It is based on the concluding remarks of the seminar ‘Crimes Against Humanity – Advancing Towards a Dedicated International Convention’ which was held in Strasbourg on 26 September 2025.