The Dynamics of Treaty Law and the Treaty Override – Perspectives on Open Constitutionalism

The article revisits the German Federal Constitutional Court’s seminal decision on the constitutionality of the (tax) treaty override. First, the article explores aspects of a treaty override under tax law and public international law in order to allow for a better understanding of this concept. Public international law provides state practice with much flexibility in adapting or even altering treaties. Thus, not every divergence of domestic law from a treaty’s wording amounts to a violation of public international law. In consequence the authors propose to classify treaty overrides as either falling within the category of a genuine (“echter”) treaty override or of a pseudo (“unechter”) treaty override which each raise different legal issues. Only in the former category is a violation of public international law through a legislator’s unilateral act at issue. However, those cases are rare and, indeed, there has been no genuine treaty override in the case before the Federal Constitutional Court. In this regard the decision of the court can be welcomed. Concerning the remaining cases of genuine treaty overrides, the Court’s holding should be modified in light of the German Basic Law’s general friendliness towards international. The authors suggest resolving these cases of genuine treaty overrides by imposing a procedural obligation upon the legislator. Under this obligation, the legislator first has to make an effort to alter the situation under international law by approaching the federal government. Only if parliament fails to sway the government, a genuine treaty override is allowed as a measure of last resort