Tax Disputes in Investment Arbitration: What 2026 Changes
Negotiators working on the proposed UN Framework Convention on Tax spent early 2026 debating a question this book answers in depth: should tax disputes between investors and states be resolved through investor-state dispute settlement (ISDS), or does routing tax cases through investment arbitration carry structural risks — high costs, inconsistent rulings, and a chilling effect on legitimate tax policy — that make it the wrong tool for the job? Cases like Vodafone and Cairn v. India, which resulted in billion-dollar awards against a sovereign state over retrospective tax measures, are exactly the precedent driving that debate.
Tax Matters in International Investment Arbitration: General Questions, Jurisdiction, Merits and Remedies, edited by Robert Danon, Sebastian Wuschka and Andreas Ziegler for Kluwer Law International, is one of the first volumes to treat this intersection systematically rather than as a footnote to either field. Robert Danon is Professor of Law at the University of Lausanne, Head of its Tax Policy Center, and former Global Chair of the IFA Permanent Scientific Committee — among the most credentialed voices working across both tax and investment law today.
The book walks through how tribunals assess jurisdiction over tax-related claims, how the Fair and Equitable Treatment standard applies when a state's tax conduct is challenged, and what remedies investment tribunals have actually awarded in tax-related cases — questions that matter directly to any counsel structuring cross-border investment in a period of tightening tax enforcement and global minimum-tax rules.
It sits well alongside the rest of our Taxation catalogue, particularly the new title on EU fiscal sovereignty, which raises parallel questions about where the boundary between tax policy and international law obligations should sit.
Q&A
Q: Can tax measures really be challenged through investment arbitration?
A: Yes — most older investment treaties do not exclude tax measures from their coverage, and cases like Vodafone and Cairn v. India show tribunals awarding damages against states over tax conduct found to breach investment protections.
Q: Why is this topic especially relevant in 2026?
A: Negotiators drafting the proposed UN Framework Convention on Tax are actively debating whether tax disputes should go through ISDS at all, or through a dedicated tax dispute mechanism — a debate this book's analysis directly informs.
Q: Does the book cover remedies, or only jurisdiction?
A: Both. It addresses jurisdiction, merits and remedies across tax-related investment disputes, not just the threshold question of whether a tribunal can hear a case.
Q: Who edited this volume?
A: Robert Danon, Sebastian Wuschka and Andreas Ziegler, drawing on contributions from leading tax and investment-arbitration specialists.
Q: Where can I buy this book?
A: From CLNZ Books at clnzbooks.com. The price includes worldwide shipping, and payment can be made by credit card or PayPal.