In a landmark development for international justice, the United Nations (UN) has taken decisive steps toward establishing the world’s first dedicated treaty on crimes against humanity. On 22 November 2024, the UN Sixth Committee, in charge of legal matters, reached a historic consensus to advance treaty negotiations, followed by the UN General Assembly (UNGA) formally adopting Resolution 79/122 on 4 December. This breakthrough came 80 years after crimes against humanity were first addressed at the Nuremberg trials.

A crucial gap

The new treaty will fill a significant gap in international law. Crimes against humanity are among the most serious violations of human rights. They can include deportation or forcible transfer of population, enforced disappearance, enslavement, extermination, illegal imprisonment or other severe deprivation of physical liberty, murder, persecution, rape, sexual slavery, forced prostitution, forced pregnancy, forced sterilisation or any other form of sexual violence of comparable gravity, torture, the crime of apartheid and other inhumane acts. These are considered crimes against humanity when they are widespread or systematic and targeted against civilian populations. Unlike war crimes, crimes against humanity can take place in non-conflict settings, as well as during conflicts. Unlike genocide, crimes against humanity don’t need to be motivated by an intent to destroy, in whole or in part, an ethnic, national, racial or religious group.

Crimes against humanity are prohibited under the Rome Statute of the International Criminal Court (ICC) and under customary international law, but unlike genocide and war crimes, covered by the Genocide Convention and the Geneva Conventions, they’re not addressed by any specific treaty. This fosters impunity and creates what some perceive to be a false hierarchy between equally serious international crimes.

The ICC plays a crucial role in prosecuting individuals for atrocity crimes, but it has significant limitations: it focuses solely on individual criminal responsibility, lacks authority over state obligations and cannot handle all cases of mass atrocities. The proposed treaty would clarify states’ obligations to prevent and punish these crimes by requiring them to outlaw crimes against humanity in domestic law, cooperate with other states to extradite or domestically prosecute perpetrators, protect victims and witnesses, guarantee fair treatment of the accused and provide mutual legal assistance. The treaty would provide for dispute resolution at the International Court of Justice so states can be held accountable if they fail to prevent or punish crimes against humanity within their territories.

A new treaty would also allow for the incorporation of decades of progress in developing international law following the adoption of the Rome Statute, particularly in relation to issues of gender justice. The new treaty should review the definition of sexual violence to include reproductive violence, use gender-inclusive language in the definition of forced pregnancy, add gender as a basis for the crime against humanity of apartheid, include forced marriage as a crime against humanity, adopt a broad and unambiguous definition of ‘victim’ and expand provisions for reparations. This requires a process that adopts a progressive perspective on gender, puts survivors and victims first, including by making adequate provisions for their participation, and is intersectional, gathering input from all affected groups.

The path to treaty negotiations

The treaty process began with the International Law Commission’s (ILC) Draft Articles on Prevention and Punishment of Crimes Against Humanity, developed through six years of consultation with states, experts and civil society organisations. In 2019, the ILC submitted these draft articles to the UNGA for consideration.

In December 2022, the UNGA established a two-year process to consider the draft articles, including sessions in April 2023 and April 2024 for states to exchange views. The successful conclusion of these discussions led to the Sixth Committee’s breakthrough in November 2024. Civil society welcomed the decision, including those working to have gender apartheid recognised as a crime under international law.

But there’s a need to be realistic about the likely challenges ahead. The resolution to start the treaty process fell far of winning unanimous support. Led by The Gambia and Mexico and co-sponsored by 97 states, it initially faced strong opposition from Russia, which ultimately withdrew its amendments but ‘dissociated’ itself from the resolution. By then, Russia had secured concessions, including a one-year delay in convening a diplomatic conference to negotiate the treaty and language meant to diminish the primacy of the ILC’s draft articles as the basis for negotiations.

The UNGA resolution established a clear timeline. The process will begin with preparatory sessions in 2026 and 2027. States must submit their amendment proposals by 30 April 2026. This will be followed by intensive three-week diplomatic conferences in 2028 and 2029, where the details of the treaty are to be hammered out. The final treaty is expected to be concluded by the end of 2029.

The ILC draft articles that negotiations will be based on provide comprehensive definitions of crimes against humanity, including detailed provisions on sexual and gender-based violence. They outline state obligations on the prevention, criminalisation, investigation and punishment of these crimes. They also set out how to protect the rights of victims and witnesses, including provisions for redress and reparations. And they call for a comprehensive system of interstate cooperation, covering critical areas such as extradition and mutual legal assistance.

Civil society input

Civil society played a vital role in shaping the draft articles. Organisations like TRIAL International made significant contributions, advocating for the elimination of statutes of limitations on crimes against humanity and the extension of this principle to civil proceedings where victims seek reparations. They called for more robust language on the liability of legal persons and recommended explicit provisions to hold corporations and others accountable. They also called for provisions on universal jurisdiction so states are obliged to prosecute or extradite, preventing perpetrators finding safe havens. They proposed improvements to crime definitions, particularly for enforced disappearance and persecution, to better align with international law, and emphasised the need to address additional issues including victim rights, reparation measures and amnesty prohibitions.

Civil society engagement led to the removal of a restrictive definition of gender from the text and contributed to proposals for strengthening victims’ rights and refining definitions of crimes such as forced pregnancy, persecution and enforced disappearances.

Over 560 civil society organisations and experts from around the world signed a statement supporting the treaty process, and many sent letters to their governments to support the initiative in the Sixth Committee. Civil society continues to urge states to actively support the development and adoption of a treaty.

The opportunity ahead

The agreement of a treaty would mark a watershed moment in international criminal justice, establishing powerful new tools to combat impunity and protect civilians from systematic or widespread attacks. While codifying crimes against humanity won’t eliminate them, a treaty would represent a crucial step toward accountability that could deter future atrocities. By establishing clear consequences for perpetrators and pathways to justice for survivors and victims, the treaty would bring some redress for the devastating human cost of these crimes.

The successful adoption of the UN resolution, despite initial opposition, signals significant international commitment to addressing these grave human rights violations. The treaty’s development now stands to benefit from the diverse perspectives brought by hundreds of civil society organisations, legal experts and others actively engaged in the process, which can only make it stronger and more relevant to the needs of survivors and victims.

As the international community embarks on this historic process, the treaty negotiations offer a once-in-a-generation opportunity to strengthen global mechanisms for preventing and punishing atrocity crimes, while ensuring justice and redress for survivors. The result could reshape how the world responds to some of humanity’s most serious crimes.

But significant challenges lie ahead. Some states will likely attempt to delay negotiations, reduce the treaty’s scope and water down enforcement mechanisms. Overcoming these obstacles will require supportive states to work closely with civil society to maintain momentum and develop and defend a strong treaty. They should get behind the treaty process if they want to be on the right side of history.

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