What exactly does it mean to say that "legal relations" are becoming "internationalized"? For me, the concept is in large measure a vertical question: the degree to which international law is affecting (some might say encroaching on) traditional domestic law, particularly state law. This is particularly so with treaty law. In the United States at least, internationalization might be thought of as simply another arm of federalism, with Congress stipulating that certain sales of goods will be governed by international law, not the Uniform Commercial Code. Or that a certain category of child adoptions will be governed by federal treaty law rather than state family law. Or that state and local officials in Pima County, Arizona, should inform a German suspected of committing murder of his federal rights under the Vienna Convention on Consular Relations. Such internationalization is not simply Missouri v. Holland redux, in which Congress is bypassing normal federalist restraints to achieve ends it could not achieve through other means. No, internationalization reflects the concept that the political branches are willing to pass laws or enter into compacts with other states to regulate foreign and interstate commerce, to define and punish offences against the law of nations, to lay and collect duties, and to make other laws that are necessary and proper to execute its powers.

But obviously the internationalization of legal relations is more, much more, than just federal preoccupation with fields that have been within the reserved powers of the state. In its essence, internationalization reflects the realities of modern life that relationships-family, business, employment, private-public-are changing in a way that increasingly transcends traditional borders and boundaries.