This article analyzes the American Clean Energy and Security Act under international environmental law and standards. The Act requires that importers pay a fee if certain requirements regarding the country and sector are satisfied. The article presents general difficulties with enforcing international environmental law, namely, the absence of a unitary government. Next, the article describes the following sources of international law: custom, treaties, soft law, and non-binding declarations. I conclude that the carbon tariffs from the American Clean Energy and Security Act are inconsistent with both hard and soft international environmental law
