This Article provides an exhaustive typology of the uses of foreign law in order to provide insight into whether foreign law can appropriately be used in constitutional interpretation, when it can be used, and what the stakes and parameters are in each case. In doing so, the Article addresses two significant problems in the debate on foreign law.
First, much of the commentary has focused on the justifications for using foreign law and the principled or practical arguments against using foreign law. But the focus on the why of foreign law has obscured the more basic question about the ways in which foreign law can be used, that is, the how of foreign law. Focusing on the why of foreign law threatens to generalize arguments into debates on "foreign law" as a whole when debating particular methods of foreign law usage may be more helpful. Some methods of use may be more easily justified and others totally unjustifiable.
The second problem is one of exhaustiveness: Some scholars have recognized the need to focus on the how of foreign law, but they have identified only a limited set of ways in which foreign law could be used. This limited categorization of foreign law usage prevents clear evaluation of which uses are appropriate. This Article's typology demonstrates that most uses of foreign law are not problematic, and as a result, the foreign law debate should focus specifically on the few potentially problematic uses, rather than on "foreign law" more generally.
I. ARGUMENTS ABOUT THE USE OF
A. Arguments from Liberal Democracy
B. Arguments from Accuracy
II. A TYPOLOGY OF FOREIGN LAW
A. Unproblematic Uses of Foreign Law
Mode 1: Quoting Language
Mode 2: Illustrating Contrasts
Mode 3: Logical Reinforcement
Mode 4: Factual Propositions
B. Potentially Problematic Uses
of Foreign Law
Mode 5: Empirical Consequences
Mode 6: Direct Application
Mode 7: Persuasive Reasoning
C. Troublesome Uses of Foreign Law
Mode 8: Authoritative Borrowing
Mode 9: Aggregation
Mode 10: No Usage
These days, it seems everyone has something to say about the use of foreign law in constitutional interpretation. Sparked by the use of foreign and international materials in Atkins v. Virginia (1) and Roper v. Simmons, (2) commentators have written much on whether and when foreign law can be appropriately considered in constitutional interpretation. (3) In opinions or speeches, virtually every Supreme Court Justice has weighed in: Justice Thomas considers foreign law to be similar to "moods, fads, or fashions." (4) Justice Scalia thinks that foreign law can make the opinions of Americans "essentially irrelevant." (5) At the same time, Justice Kennedy believes the use of foreign law is a central part of American moral leadership in the world because it can help express a "unified concept of what human dignity means." (6) Justice Ginsburg thinks it merely involves "sharing with and learning from others." (7) And Justice Breyer sees foreign law as shedding "empirical light" on common problems. (8)
Although so many have weighed in on both sides of this topic, and have fleshed out so many of the important issues, (9) the literature has suffered from two important problems. First, much of the commentary has focused on the justifications for using foreign law and the principled or practical arguments against using foreign law. To be sure, this approach is of obvious purchase and considerable intellectual interest. Whether or not foreign law should be used in constitutional interpretation should be dependent on the reasons why it can or cannot be used. But the focus on the why of foreign law has obscured the more basic question about the ways in which foreign law can be used, that is, the how of foreign law. Before evaluating the principled arguments for or against foreign law, one must identify which method of usage is being judged. …