This book is an updated and developed version of the PhD thesis “Tax Treaty Making in Federations”, defended by Rik Smet on 23 June 2020 at the University of Antwerp Faculty of Law, Belgium. It contributes to the discussion on alternative solutions for the difficulties that currently exist in the treaty making practice of federal states. The author develops a new theory on how tax treaty making competence and power should be distributed between the different levels of government in federations. This work is outstanding for at least three reasons.

First, Rik Smet starts his PhD with a story about birds migrating between Canada and the southern United States. These birds were shot and killed during their migration somewhere above the centre of the United States. He explains how this triggered the anger of American ornithologists and animal activists. Starting from that bird story, the author makes the bridge to federal states and tax treaty making competences. People who can creatively connect two such, at first sight totally unrelated, topics, are scarce, but Rik Smet is certainly one of them.

Second, this PhD smoothly integrates a philosophical framework with a legal one. The author finds a delicate balance between the abstract philosophical theories of Habermas, Dworkin, and Rosanvallon on the one hand, and legal realities that govern international tax law on the other hand. Building on Rosanvallon, he introduces the new concept of “meritorious legitimacy”, which means that the legitimacy of tax treaties not only requires a suitable democratic process, but also concerns the question of whether treaties that have been concluded in the past still retain the support of society today. This triggers, for example, the question of whether countries still approve of treaties concluded years ago with tax havens. So far, these questions have remained largely unaddressed, and this PhD is an explicit call to deal with these problems.

Finally, Rik Smet does not limit his research to law in the books, but also looks at treaty making practice. Based on interviews with key actors and stakeholders, he identifies multiple practical problems and limitations, like a huge capacity issue within the Belgian department of the Federal Public Service Finance that is responsible for tax treaties.