The U.S. Supreme Court has interpreted this clause narrowly by allowing state compacts as long as they do not "encroach on the supremacy of the United States," which is protected anyway by the [[Supremacy Clause]]. ''United States Steel Corp. v. Multistate Tax Commission'' (1978). | The U.S. Supreme Court has interpreted this clause narrowly by allowing state compacts as long as they do not "encroach on the supremacy of the United States," which is protected anyway by the [[Supremacy Clause]]. ''United States Steel Corp. v. Multistate Tax Commission'' (1978). |