UNIVERSITY of PENNSYLVANIA LAW REVIEW Founded 1852 Formerly AMERICAN LAW REGISTER VOL. 163 MARCH 2015 NO. 4 ARTICLE JUDICIAL COMPARATIVISM AND JUDICIAL DIPLOMACY † DAVID S. LAW © 2015 David S. Law † Professor of Law and Professor of Political Science, Washington University in St. Louis; Martin and Kathleen Crane Fellow in Law and Public Affairs, Princeton University. This Article has benefited from the exceptional work of the editors of the University of Pennsylvania Law Review. Portions of Sections IV.D and IV.E are adapted from an article co-authored with Wen- Chen Chang entitled The Limits of Global Judicial Dialogue, which appeared in 2011 in the Washing- ton Law Review. That material is incorporated here with the blessing of Professor Chang, to whom I remain deeply indebted. Earlier versions of this Article were presented at faculty workshops at American University, Fordham Law School, Tulane Law School, the University of San Diego, Washington University in St. Louis, and Whittier Law School; the Comparative Constitutional Law Roundtable at the George Washington University Law School; the Centre for Comparative and Public Law at the University of Hong Kong; and the Centre for Public Governance and Law at Yonsei Law School. I am deeply grateful to Miri Joo, Chien-Chih Lin, Sachiyo Miller, HyunTae Roh, Norimitsu Shirai, Ethan Brandt, Hyun Jin Chung, and Ho Jun Yang for indispensable research assistance in a variety of languages; to the Center for Empirical Research in the Law at Washington University in St. Louis for funding the translation of Korean-language materials; and to Francesca Bignami, Cora Chan, Tom Clark, Erin Delaney, Martin Flaherty, David Fontana, Martin Gelter, Danny Gittings, Oren Gross, Chaihark Hahm, Johanna Kalb, Ken Kersch, David Kosar, Ron Krotoszynski, Chulwoo Lee, Keun-Gwan Lee, Tom Lee, Jeffrey Lubbers, Manoj Mate, (927) 928 University of Pennsylvania Law Review [Vol. 163: 927 By global standards, the U.S. Supreme Court is unusual in a number of respects, but one of its most distinctive characteristics is its reluctance to engage in comparative constitutional analysis. Much has been said on the normative question of whether and in what ways the Court ought to make use of foreign constitutional jurisprudence. Rarely, however, do scholars broach the underlying empirical question of why some courts make greater use of foreign law than others. To identify the causes of comparativism, a behind-the-scenes investigation was conducted of four leading courts in East Asia: the Japanese Supreme Court, the Korean Constitutional Court, the Taiwanese Constitutional Court, and the Hong Kong Court of Final Appeal. The results of this investigation highlight the crucial role of institutional and resource constraints in shaping judicial behavior but also pose an unexpected challenge to traditional conceptions of the role and function of constitutional courts. Evidence from interviews conducted with numerous justices, clerks, and senior administrators suggests that a combination of mutually reinforcing factors creates the conditions necessary for comparativism to thrive. The first factor is institutional capacity. A court that lacks institutional mechanisms for learning about foreign law, such as the recruitment of law clerks with foreign legal expertise or the use of researchers who specialize in foreign law, is unlikely to make more than sporadic use of foreign law. The second factor is legal education. Even the most elaborate of institutional mechanisms for facilitating comparativism is unlikely to be effective unless it is backed by a system of legal education that produces an adequate supply of lawyers with both an aptitude and appetite for comparativism. Investigation of the reasons for which courts engage in comparativism also reveals a hidden underlying phenomenon of judicial diplomacy. Unlike other judicial practices such as textualism or originalism, comparativism is not merely a means by which judges perform legal and adjudicative functions; it can also be a form of diplomatic activity. When constitutional courts demonstrate mastery of foreign law or host foreign judges, their goals may not consist exclusively, or even primarily, of writing stronger opinions or winning over domestic audiences. They may also be competing with one another for international influence or pursuing foreign policy objectives, such as promotion of the rule of law and judicial independ- ence in other countries. The concept of judicial diplomacy helps to explain why constitutional courts engage in a number of practices that are only tenuously related Fernanda Nicola, Anselmo Reyes, Woo-Young Rhee, Larry Solum, Nick Stephanopoulos, Brian Tamanaha, Steve Vladeck, Po Jen Yap, Simon Young, and David Zaring for enormously valuable suggestions and feedback. Above all, this Article would not have been possible without the generous cooperation and unstinting candor of numerous judges, law clerks, and court officials in Hong Kong, Japan, Korea, and Taiwan who provided crucial first-hand information and, in some cases, reviewed portions of this Article for factual error. The fact that they are not acknowledged here by name reflects expectations of anonymity and must not be mistaken for lack of gratitude. 2015] Judicial Comparativism and Judicial Diplomacy 929 to the act of adjudication. Although the U.S. Supreme Court rarely practices constitutional comparativism, it is an active practitioner of judicial diplomacy in other forms. INTRODUCTION: THE DIVIDE BETWEEN AMERICAN AND GLOBAL CONSTITUTIONALISM ............................................................930 I. THE CHALLENGES OF MEASURING COMPARATIVISM: METHODOLOGY AND DATA COLLECTION .............................. 945 A. Case Selection: Most-Similar Versus Most-Different Cases ...............949 B. Data Collection: A Structured-Focused Approach ........................... 952 II. THE JAPANESE SUPREME COURT ............................................ 953 A. Level of Foreign Law Citation .................................................... 953 B. Level of Foreign Law Usage ........................................................ 953 C. Jurisdictions Considered .............................................................. 957 D. Level of Foreign Law Expertise ................................................... 958 E. Level of Interaction with Foreign Courts ....................................... 961 III. THE KOREAN CONSTITUTIONAL COURT ................................ 962 A. Level of Foreign Law Citation .................................................... 962 B. Level of Foreign Law Usage ........................................................ 962 C. Jurisdictions Considered .............................................................. 963 D. Level of Foreign Law Expertise ...................................................964 1. The Justices Themselves ....................................................964 2. Constitutional Research Officers (CROs) ........................... 967 3. Constitutional Researchers (CRs) ..................................... 969 4. Academic Advisers ............................................................ 970 5. Experts Hired by the Parties ............................................. 971 6. The Constitutional Research Institute ................................ 972 E. Level of Interaction with Foreign Courts ....................................... 974 IV. THE TAIWANESE CONSTITUTIONAL COURT ............................976 A. Level of Foreign Law Citation .................................................... 976 B. Level of Foreign Law Usage ........................................................ 977 C. Jurisdictions Considered .............................................................. 979 D. Level of Foreign Law Expertise ................................................... 980 E. Level of Interaction with Foreign Courts ....................................... 982 V. THE HONG KONG COURT OF FINAL APPEAL .......................... 986 A. Level of Foreign Law Citation .................................................... 986 B. Level of Foreign Law Usage ........................................................ 986 C. Jurisdictions Considered .............................................................. 989 D. Level of Foreign Law Expertise ...................................................990 1. The Entrenched Legacy of British Rule .............................. 991 930 University of Pennsylvania Law Review [Vol. 163: 927 2. Participation of Overseas Judges and Lawyers .................... 992 3. The Foreign Education of Lawyers and Judges ...................994 4. Research Assistance .......................................................... 995 E. Level of Interaction with Foreign Courts ...................................... 996 VI. CONVENTIONAL EXPLANATIONS FOR COMPARATIVISM ............997 VII. DIPLOMATIC EXPLANATIONS FOR COMPARATIVISM ............. 1003 VIII. INSTITUTIONAL EXPLANATIONS FOR COMPARATIVISM ........ 1009 A. The Role of Institutional Design .................................................. 1010 B. The Role of Legal Education ....................................................... 1015 CONCLUSION: JUDICIAL DIPLOMACY AND JURISPRUDENTIAL NETWORKS ......................................................................... 1020 INTRODUCTION: THE DIVIDE BETWEEN AMERICAN AND GLOBAL CONSTITUTIONALISM By global standards, American constitutionalism is unusual—or, as some prefer to say, exceptional1—in many respects. Much of what makes it so atypical