The Supremacy Clause includes treaties in the list of supreme laws which state judges are bound to uphold against conflicting state laws. However, as the U.S. Supreme Court most recently affirmed in Medellin v. Texas, not all Article II treaties receive this Supremacy Clause effect immediately upon ratification. Some treaties, known as non-self-executing treaties, are domestically unenforceable by United States courts until passage of federal legislation implementing the treaty. Based on this distinction between non-self-executing and self-executing treaties, courts have disagreed as to whether an implemented non-self-executing treaty can preempt state law or whether only the implementing legislation can have such Supremacy Clause effect.

This Note argues that the inclusion of the words “all Treaties” in the language of the Supremacy Clause is grounded in the decision that the federal government would dominate national foreign relations and in the necessity of reigning in conflicting state actions in that area. Due to this constitutional framework, once a non-self-executing treaty has been properly implemented, in some cases it can and should preempt state law. In short, implemented non-self-executing treaties should have Supremacy Clause effect where it is necessary to uphold United States foreign policy decisions and to stop states from placing the United States in breach of international obligations that have already been domestically executed.