However, a small but vocal group of critics has used op-ed pages and blogs to rail against Koh's nomination. They argue that his support for "transnational" law threatens American sovereignty and the Constitution's supremacy. Such charges have produced caricatures of Koh and the American legal system that are incomplete and inaccurate.
Koh's critics conflate two issues: first, international law's effect on U.S. law, and, second, the use of foreign law to interpret the U.S. Constitution and statutes. Neither topic is original to this dust-up; isolationists have long favored governing America with an inward eye, entirely independent of the rest of the world. Proponents of international engagement, by contrast, invoke an American tradition of valuing international law and the lessons of other countries' experiences.
The idea that there are international laws that can somehow affect U.S. behavior may appear antithetical to ideas of American independence or sovereignty. But, as our nation's founders repeatedly recognized, international law actually preserves U.S. sovereignty. It helps ensure that other nations respect U.S. products and citizens beyond our borders; engage in joint responses to common problems, such as terrorism and piracy; and agree to basic standards of behavior, such as the prohibition on genocide.
Koh's critics gloss over the fact that the United States willingly enters into treaties that bind it. Pursuant to Article VI of the Constitution, these treaties constitute "the supreme Law of the Land," equivalent to federal statutes and binding on state judges. With respect to international customs that rise to the level of legal obligations, the Supreme Court long ago declared that such "international law is part of our law."
The United States can still avoid these rules by objecting to them from the beginning or, through Congress, overriding them later. And their interpretation remains firmly in U.S. hands. However, while Koh and his critics may debate the content of international law, it is far too late to suggest we can ignore it.
Similar misunderstandings permeate claims that Koh would let "foreign" laws govern U.S. court cases. Neither Koh nor any serious American lawyer disputes the Constitution's supremacy within the U.S. legal system. What Koh has advocated - along with many others - is the educational value of other countries' experiences in interpreting our Constitution and statutes.
At least six current and former Supreme Court justices have endorsed using foreign materials this way. Today's justices cite law review articles, social science studies, and even Gilbert & Sullivan in their opinions. Why not also the experiences of foreign judges? Doing so does not give foreigners control over the Constitution any more than citing a show tune gives composers that power. Foreign laws never bind U.S. judges, but they can be a useful resource.
Suggestions that Koh's appreciation of foreign and international law is somehow un-American misrepresent who we are as a nation. International law and a willingness to learn from others' experiences are part of our DNA.
One opponent expressed horror at Koh's willingness to examine U.S. law with a "decent respect to the opinions of humankind." Critics would do well to consider that phrase's origin: the Declaration of Independence. Koh's respect for international law and the experiences of other peoples does not deny the greatness of America and our Constitution; it affirms it.
Duncan Hollis is an associate professor at Temple University's Beasley School of Law and has served in the State Department Legal Adviser's Office. Christopher Borgen is an associate professor at St. John's University School of Law in New York City. Both contribute to the blog Opinio Juris, at www.opiniojuris.org.