A Vienna whirl through the treaty maze

This publication is a timely and authoritative contribution to treaty law. As the 1969 and 1986 Vienna Conventions continue to underpin contemporary international legal relations, the need for a commentary that combines doctrinal rigour with responsiveness to jurisprudence is clear.

A major strength of the work lies in its systematic examination of each provision’s object and purpose, closely reflecting the interpretative approach of international courts and tribunals. Equally valuable is its consistent analysis of the customary status of each article. This allows practitioners to determine applicable rules when dealing with non-parties to the VCLT and mixed treaty regimes, such as those involving the EU. This makes the commentary directly operational for litigation, treaty drafting and legal advice.

The treatment of interpretative issues is robust. The volume integrates jurisprudence from the International Court of Justice, multiple arbitral tribunals and regional courts. This reflects the pluralism of modern treaty adjudication.

Another defining feature is the book’s extensive use of the travaux préparatoires of both conventions. There is detailed engagement with International Law Commission materials, diplomatic conference records and early state practice. The commentary turns preparatory work into a practical interpretative tool, particularly in respect of the treaty-making powers of international organisations under the 1986 convention and the rules on termination, withdrawal and material breach.

The unified treatment of the 1969 and 1986 conventions enhances the volume’s utility. Despite the limited ratification of the latter, its relevance for advising international organisations is clear. By addressing both instruments side by side, the commentary clarifies where the 1986 convention codifies custom, where it innovates and where uncertainties persist.

For practitioners, the commentary provides a sophisticated but accessible analysis of treaty interpretation. 

Simone Mamini is a doctoral researcher in law and a visiting lecturer in maritime and international law at City St George’s, University of London