This book has a thesis: that a coherent international tax regime exists, embodied in both the tax treaty network and in domestic laws, and that it forms a significant part of international law (both treaty-based and customary). The practical implication is that countries are not free to adopt any international tax rules they please, but rather operate in the context of the regime, which changes in the same ways international law changes over time. Thus, unilateral action is possible, but is also restricted, and countries are generally reluctant to take unilateral actions that violate the basic norms that underlie the regime. Those norms are the single tax principle (i.e., that income should be taxed once – not more and not less) and the benefits principle (i.e., that active business income should be taxed primarily at source, and passive investment income primarily at residence).

This thesis is quite controversial. Several prominent international tax academics and practitioners in the United States (e.g., Michael Graetz, David Rosenbloom, Julie Roin, Mitchell Kane) and elsewhere (e.g., Tsilly Dagan) have advocated the view that there is no international tax regime and that countries are free to adopt any tax rules they believe further their own interests. Other prominent tax academics (e.g., Hugh Ault, Yariv Brauner, Paul McDaniel, Diane Ring, Richard Vann) and practitioners (e.g., Luca dell'Anese, Shay Menuchin, Philip West) have supported the view just advocated. However, there is no coherent exposition of this view in the academic or practical literature.