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On the Interaction of International Tax Law and Domestic Law: A Plea for a Step Back to Theory of Law

The abuse of tax conventions and their use to circumvent domestic tax law rules has been a major concern since the development of modern tax treaties in the 1960s. In this regard, the OECD pointed out as early as 1977 that international tax planning schemes were contrary to fiscal equity, harmed public budgets and distort international competition. To resolve such issue with tax treaties, States developed two reasoning lines. On the one hand, they began to apply those rules and doctrines that were developed against the abuse of domestic tax rules to tax treaties; on the other hand, countries claimed and started to introduce measures in treaties against their abuse. However, questions and issues arose as soon as they began to apply such rules. First, whether domestic rules were applicable to treaty-covered cases; second, the relationship between general and specific anti-avoidance rules in treaty scenarios. All in all, the topic has not been resolved despite more than 70 years of discussions and controversy. Moreover, commentaries and reports on the issue pose several inconsistencies and misunderstandings. Neither the United States nor the OECD or United Nations have developed a consistent position. It therefore seems that the topic remains unresolved and in need of an in-depth analysis of the issue taking into account basic rules of the theory of law. It is noteworthy to point out that the topic is of utmost importance since it defines which tools are applicable to combat tax avoidance, the possible preference of one of them and their limits. By doing so, the issue defines the legal frontiers of the battle against tax avoidance, which needs little justification of its importance. Thus, by defining such limits, this study would also help to define the tax policy against tax avoidance, providing the tools to support the studies that would lead to establish whether there is a need for new anti-avoidance rules or if existing rules could succeed in preventing tax avoidance. To do so, this work aims to (i) organize and make a systematic study of the main issues on the interaction of anti-avoidance rules, (ii) propose a theoretical framework that serves as basis to resolve conflicts between anti-avoidance rules, (iii) analyse the main arguments and reasoning on the interaction of anti-avoidance rules and (iv) analyse some specific examples on the interaction of treaties and anti-avoidance rules. To this end, in the first part we will briefly point out and analyse the main arguments used to support the compatibility of domestic anti-avoidance rules and treaties, as well as the arguments sustaining the current state of the art on the compatibility of treaty anti-avoidance rules. In the second part we will briefly analyse the structure of the legal systems and the relationships between rules and principles within the legal system from a theoretical perspective. Lastly, we will apply the theoretical findings from the second part to the current positions on the relationship between domestic and treaty-based rules, and between conventional rules.