As the UN Moves to Codify Crimes Against Humanity, a New Book Revisits the Legality Principle
On 19 January 2026, a UN preparatory committee opened three years of negotiations toward the first-ever international treaty on crimes against humanity — closing a gap that has stood since the Nuremberg Tribunal nearly 80 years ago. Roughly 100 states, led by Mexico and The Gambia, are pushing to complete the treaty by 2028–2029, while others have asked for further study. Among the live debates: whether to add specific acts to the treaty's list of crimes, including forced marriage, gender apartheid and crimes against people with disabilities.
That debate is exactly where Judicial Discretion in the Interpretation of International Crimes: Revisiting the Legality Principle, by Ligeia Quackelbeen (Hart Publishing, July 2026), lands with real timing. The book asks a question treaty drafters and judges alike are wrestling with right now: once a crime is written into law, how far can courts go in interpreting its scope before they cross from applying the law to making it? Quackelbeen's two-step framework — first identify the applicable law, then test whether it actually criminalises the conduct — gives a rigorous answer grounded in the legality principle, nullum crimen sine lege.
The book is not abstract theory. It is built around two case studies with direct bearing on the current treaty talks: the contested "organizational policy" element in crimes against humanity, and the emerging offence of forced marriage — the very addition now on the table at the UN. For practitioners, the book offers a tested methodology for arguing the limits of judicial interpretation before international courts and tribunals. For scholars, it supplies a domestic-criminal-law lens too rarely applied to international criminal law. For treaty negotiators and the diplomats advising them, it is a timely reminder of where courts have already had to draw these lines in practice.
For academic and institutional law libraries building or maintaining an international criminal law collection, this title belongs alongside the standard references on the Rome Statute and ICC jurisprudence — it is one of the few 2026 releases to engage directly with a definitional debate now unfolding at the UN in real time.
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Q&A
What is the legality principle in international criminal law?
The legality principle (nullum crimen sine lege) holds that no one may be criminally punished except for conduct clearly established as criminal under the applicable law at the time it was committed.
Why is the UN negotiating a new crimes against humanity treaty in 2026?
No dedicated global treaty on crimes against humanity has ever existed — unlike genocide or war crimes — so a UN preparatory committee began three-year negotiations in January 2026 to close that gap.
Is forced marriage being considered as a crime against humanity under the new treaty?
Yes — forced marriage is among the acts states are debating adding to the treaty's list, a question this book examines directly through its forced marriage case study.
What is the organizational policy element in crimes against humanity?
It is a contested requirement concerning whether an attack against a civilian population must be pursuant to an organizational policy — one of the book's two central case studies.
Where can I buy Judicial Discretion in the Interpretation of International Crimes?
This title is available now from CLNZ Books, with worldwide shipping and secure payment by card or PayPal.