3 Relationship with other Areas of International Law
This chapter discusses the interaction of the international tax regime with other international law disciplines such as trade law, investment treaty law, and human rights law. Moreover, it contains an overview of tax rules in non-tax agreements such status of force agreements or headquarter agreements signed by host states with international organizations. The goal is to outline how these other legal regimes influence the international tax regime. The most obvious example is trade law as it limits the legislative leeway of states in tax matters in various ways. In particular, obligations derived from most-favoured nation and national treatment clauses are of great importance for tax policy and will be discussed in detail. But also, investment treaties provide for several policy limitations. In order to outline the interaction between trade law, investment treaty law, and the international tax regime, reference is made so several decisions of international courts.