After the ICJ's Right to Strike Opinion, a New Edition Reckons with How Treaties Are Actually Interpreted
On 21 May 2026, the International Court of Justice issued its Advisory Opinion on the Right to Strike, concluding by a 10–4 majority that ILO Convention No. 87 — which contains no explicit reference to strike action — nonetheless protects that right. The Court reached that conclusion through the interpretive framework of the Vienna Convention on the Law of Treaties: reading "activities" in Article 3(1) according to its ordinary meaning and the Convention's object and purpose, and treating a "significant majority" of state practice, short of unanimity, as a legitimate supplementary means under Article 32. The dissent was sharp. Judge Tomka accused the majority of treating state consent "not as the foundation of treaty interpretation, but as a residual obstacle to be overcome" — a methodological dispute that has already generated extensive commentary among international lawyers.
That dispute is exactly the terrain mapped by Richard Gardiner and Joseph Klingler's Treaty Interpretation (ISBN 9780192873408), now in its third edition from Oxford University Press. The book works through Articles 31 to 33 of the Vienna Convention rule by rule, showing through decades of case law — from the ICJ to WTO panels to investment tribunals — how the general rule and its supplementary means actually operate when courts disagree about method, not just outcome. This edition folds in the International Law Commission's more recent conclusions on subsequent agreements and subsequent practice, the very interpretive tool at the centre of the Right to Strike controversy.
For practitioners, the value is concrete. Counsel assessing whether a silent treaty provision can be read to cover an unaddressed right — the exact question the ICJ faced with Convention No. 87 — can trace the same Article 31 analysis chapter by chapter. Treaty negotiators drafting new multilateral instruments can use the book's treatment of subsequent practice to anticipate how a clause's silence might later be filled in by a tribunal. And arbitral tribunals and WTO panelists, who cite this work routinely as an authority on interpretive method, gain an updated single-volume reference rather than working from a superseded edition.
For academic and institutional law libraries, this remains the standard single-volume treatment of treaty interpretation methodology, and the ICJ's 2026 opinion has only sharpened demand for it: public international law faculties, moot court programmes, and international dispute resolution practice groups will be citing both the opinion and this edition side by side for years.
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Q&A
Q: What does the third edition of Treaty Interpretation add?
A: It incorporates recent jurisprudence from international and domestic courts, and the International Law Commission's more recent conclusions on subsequent agreements and subsequent practice as a means of interpretation.
Q: How does this book relate to the ICJ's 2026 Right to Strike opinion?
A: The opinion turned on exactly the Vienna Convention interpretive tools — ordinary meaning, object and purpose, and subsequent practice — that the book analyses rule by rule across ten chapters.
Q: Who is this book written for?
A: International law practitioners, diplomats and treaty negotiators, judges and tribunal members, and academic and institutional law libraries.
Q: Is this only useful for litigators?
A: No — the book is equally aimed at diplomats and treaty negotiators who need to anticipate how the text they draft will later be interpreted.
Q: Where can I buy Treaty Interpretation 3rd ed?
A: Through CLNZ Books, with worldwide delivery for university libraries, law firms, and individual professionals.
Q: What is the ISBN for this title?
A: ISBN 9780192873408.