It is inappropriate for the US Supreme Court to defer to international law. It is the Supreme Court's obligation to serve the interests of the United States. In addition, the Supreme Court has no jurisdiction outside the United States and it's territories. The purpose of the Supreme Court is to uphold the constitutionality of actions taken by citizens of the United States. Nothing less, nothing more. Any contention to the contrary is incorrect. We are NOT a "sub-territory" of the world. We are a sovereign nation. Our politicians do not even have the authority to sign a treaty which compromises our authority if they wanted to. The constitution prevents any of our leaders from "selling us out" to international interests.
The Supreme Court's job is to interpret the constitution as it relates to the case at hand. International law has absolutely nothing to do with the constitution.