The law of other states.

• Author: Posner, Eric A.

INTRODUCTION I. THE JURY THEOREM AND FOLLOWING OTHER STATES A. A Heated Controversy B. Decisions and Information C. The Basic Argument D. An Initial Puzzle and Underlying Assumptions II. THE JUDGMENT CONDITION III. THE SIMILARITY CONDITION A. Factual Differences B. Moral Differences 1. Prerequisites 2. Moral practices and moral contenders 3. What's relative? C. Legal and Institutional Differences D. The Regression Approach E. Are Only Liberal Democracies Relevant? IV. THE INDEPENDENCE CONDITION AND CASCADES V. FOREIGN LAW VERSUS INTERNATIONAL LAW VI. JUDICIAL COMPETENCE AND A FRAMEWORK A. Issues of Administrability B. Principles C. A Framework D. Beyond Courts VII. SOME EMPIRICAL IMPLICATIONS A. The Young State Hypothesis B. The Good State Hypothesis C. Competing Theories CONCLUSION INTRODUCTION

Consider the following cases:

1. The Supreme Court of Texas is deciding whether to give a broad reading to the "public policy exception" to its general rule that employment is at will. The court is concerned that a broad reading, which would intrude on the ability of employers to manage the workplace, might have serious adverse effects on the economy of Texas. Because of that concern, the court investigates the practices of other states. It notices that most state courts have read the public policy exception broadly, and have done so without causing noticeable adverse effects on the economies of their states. Influenced by those decisions, the court adopts a broad reading of the public policy exception.

2. The Supreme Court of Vermont is deciding whether to rule that under its state constitution, discrimination on the basis of sex is subject to "strict scrutiny," which would ensure that such discrimination would almost always be struck down. The Supreme Court of Vermont consults the practices of other states and discovers that the overwhelming majority of state courts interpret their constitutions so as to subject sex discrimination to strict scrutiny. It follows the practice of that overwhelming majority.

3. The Supreme Court of the United States is deciding to rule whether government may execute people under the age of eighteen. (2) Believing that the question is difficult, the Court decides to consult the practices of other nations. (3) It happens that few nations impose the death penalty on people under the age of eighteen. Influenced by this, the Court rules that the United States may not constitutionally do so.

   The practice of consulting "foreign precedents" has received a great deal of attention in connection with recent decisions of the Supreme Court of the United States. (4) In those decisions, the Court has referred to comparative law in deciding whether a statute or state practice violates the U.S. Constitution: The references have proved exceptionally controversial. (6) But in some ways, it is quite standard to refer to the decisions of other jurisdictions, and the debate over the references of the Supreme Court should be understood in the context of that standard practice. Within the United States, for example, state courts frequently refer to the judgments of other state courts in ruling on questions of private and public law, and indeed in ruling on the meaning of state constitutions. (7) Significant numbers of out-of-state citations have been found in Arkansas, (8) New York, (9) Kansas, (10) Ohio, (11) Montana, (12) California, (13) and North Carolina, (14) among others. (15) A study of twelve states found that state courts cited out-of-state courts in no less than 34.8% of their decisions, with substantially higher percentages in Massachusetts, Arizona, and Vermont. (16) It is not taken to be illegitimate, or even controversial, for one state to consult the practices of others in deciding on the meaning of the state's founding document. (17) On the contrary, "comparative law" is a routine and uncontroversial feature of the jurisprudence of state courts. (18)

   Many national courts regularly consult "foreign precedents" in deciding on the meaning of their own constitutions. (19) The Supreme Court of Ireland cites foreign law with some frequency. (20) Between 1994 and 1998, South African Supreme Court and Constitutional Court decisions made no fewer "than 1258 references to American, Canadian, British, German, European, and Indian courts." (21) The Supreme Court of Israel makes heavy use of foreign law in multiple domains. (22) At least in some cases, German courts consult foreign courts as well. (23) Canadian courts hardly restrict themselves to Canadian precedents, (24) and Australian courts reach far and wide. (25) Use of foreign law also occurs, if tacitly, in Italy and France. (26) In Britain the practice is common, and it appears to be growing over time. (27) Consultation of foreign law seems to be the rule, not the exception.

   Our goal here is to set out a framework for assessing the question of whether courts should consult the practices of other states, either domestically or nationally. Our starting point is admittedly unusual: the Condorcet Jury Theorem. (28) As we use it here, the Jury Theorem formalizes the simple intuition that the practices of others provide relevant information, and that courts ought not to ignore such information. We suggest that the Jury Theorem provides the simplest argument for following the practices of other states: it suggests that if the majority of states believe that X is true, there is reason to believe that X is in fact true. In our view, the Jury Theorem also provides the foundation not only for following the practices of other states, but also for seeing when and why it is hazardous to do so. In particular, the Jury Theorem suggests that the practices of other states provide useful information when three conditions are met: those practices reflect the judgment of the affected population or decision-makers; the other state is sufficiently similar; and the judgment embodied in the practice of the other state is independent.

   In supplying a governing framework, we attempt to give structure to a debate that so far has consisted mainly of ad hoc (though often reasonable and illuminating) arguments for or against following the practices of other states. Our hope is that this framework might have broad applicability to many situations in which legal authorities are deciding whether to consult the decisions of other legal actors. Suppose, for example, that it is ultimately agreed that in interpreting the U.S. Constitution, the U.S. Supreme Court should not consult the practices of other nations. It may remain possible that other high courts, interpreting their own constitutions, should consult such practices. The analysis here might justify and inform such consultation. The same analysis might apply not only to state courts operating domestically, but also to judgments by legislatures, of states or of nations, that are deciding whether to follow the majority view of apparently relevant others. (29) In structuring a program to protect endangered species, the legislature of Montana may or may not want to follow the general practices of other state legislatures; in deciding on national energy policy, or in seeking to control global warming, Congress may or may not want to adopt the approaches of other nations. For such judgments, the Condorcet Jury Theorem provides a helpful place to start.

   Four clarifications before we begin: First, we assume initially that judges can interpret foreign materials both easily and adequately. It is important to see how the analysis should proceed if judges could undertake it properly; but of course there is no assurance that they can. In Part VI, we will discuss the extent to which more realistic assumptions about judicial capacities would complicate our basic claims, and perhaps justify a departure from them in the interest of easy administration. Second, we are concerned with the use of foreign decisions as relevant information for resolving disputes, not with the use of foreign decisions as "precedent"; indeed, we do not believe that anyone seeks to use foreign decisions in that way. (30) Third, we assume that the Supreme Court has been candid about its reasons for using foreign sources, and so the controversy is over doctrine and not judicial rhetoric. (31) The fact that state courts regularly use "foreign" sources in the same way that the Supreme Court has done provides some assurance on this count.

   Finally, we hope that our analysis will prove useful to people with diverse views about the proper interpretation of the Constitution. It is tempting and to some extent correct to think that originalism, (32) by itself, excludes reference to foreign precedents; if the Constitution means what it originally meant, the contemporary practices of foreign nations are usually immaterial. (33) And indeed, our analysis will help show why, exactly, those with different approaches to constitutional interpretation reach different conclusions about the relevance of foreign law. But at least in some cases, our conclusions should be attractive to originalists as well as to those who reject originalism or prefer some middle way. Whenever the Court has to make a factual or moral inquiry that is required by original understanding, then the framework provided by the Jury Theorem provides a useful place to start. (34) Of course some theories of constitutional interpretation will be relatively less willing to ask about the factual and moral questions on which comparative law might bear, and we shall pay considerable attention to variations on that count.

   Our emphasis is normative, but the central argument has positive as well as normative implications. Indeed, we are willing to hypothesize that an implicit understanding of the Condorcetian argument helps explain a wide range of existing practices, including the fact that state courts consult the legal materials of other state courts more than national courts consult the legal materials of foreign...