The Citation and Depreciation of U.S. Supreme Court Precedent

• Published date: 01 June 2013
• Date: 01 June 2013
• Author: Ryan C. Black,James F. Spriggs
• DOI: http://doi.org/10.1111/jels.12012

The Citation and Depreciation of U.S.

Supreme Court Precedent

Ryan C. Black and James F. Spriggs II*

An enduring piece of legal wisdom contends that the value of court opinions depreciates as

they age and a variety of factors lead some cases to depreciate faster than others. We measure

depreciation as the change in the frequency with which Supreme Court cases are cited as a

function of their age. We then examine whether the rate of depreciation varies systematically

based on ideological considerations, opinion characteristics, and citation history. Our results

indicate, first, that precedents depreciate rather quickly and, for example, depreciate about

81 percent and 85 percent between their first and 20th years of age at the Supreme Court

and courts of appeals, respectively. Second, few of the variables in our analysis have any

appreciable influence on the pace of depreciation. Two variables capturing the citation

history of a case have the most notable influence on depreciation, but even their effects are

reasonably modest and somewhat short-lived. Third, while our study focuses on depreciation

(i.e., the change in the frequency of citation over time), it also produces an important

implication for citation itself (i.e., the number of times a case is cited in a given year). We

show that prior studies significantly overestimate the effect of almost every variable used to

explain citation rates because those variables become substantially less influential as cases

age. Future studies must therefore take into account that the effect of an independent

variable on citations is conditional on the age of a precedent. This study therefore contrib-

utes to our understanding of the process by which law, as observed through citations to cases,

changes.

I. Introduction

An enduring piece of legal wisdom contends that the informational value of court opinions

depreciates as they age. As society evolves and law changes due to economic, social, and

political developments, the extent to which a precedent remains pertinent for deciding

legal disputes diminishes. As judges analogically reason their way to conclusions, older cases

*Address correspondence to James Spriggs, Department of Political Science, Washington University in St. Louis,

St. Louis, MO 63119; email: jspriggs@wustl.edu. Black is Assistant Professor of Political Science, Michigan State

University; Spriggs is Sidney W. Souers Professor of Government and Chair, Department of Political Science,

Washington University in St. Louis.

Spriggs recognizes funding from the National Science Foundation (Law and Social Science, SES-0550451). A

previous version of this article was presented at the 2009 Conference on Empirical Legal Studies. We appreciate the

comments of participants at colloquia at Washington University in St. Louis School of Law, the University of Texas at

Austin’s Business School, University of Rochester, and University of California, Merced. We also thank Brandon

Bartels, James Fowler, Matt Gabel, Jeff Gill, Tom Hansford, Pauline Kim, Michael Solimine, and David Stras for

helpful comments.

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Journal of Empirical Legal Studies

Volume 10, Issue 2, 325–358, June 2013

325

are less likely to contain issues, principles, and reasoning appropriate for contemporary

legal problems. Landes and Posner (1976:263) provide one of the earliest explicit argu-

ments in this regard, stating that a precedent “depreciates in an economic sense because

the value of its information content declines over time with changing circumstances . . .”

thus reducing “the value of precedents as a source of legal doctrine.”

Precedents are a central element in the U.S. judiciary and create rules providing

decisionmakers with information that enables them to make predictions about the conse-

quences of alternative courses of action (Cardozo [1921] 1964:19–35; Holmes 1897; Hurst

1956; Wahlbeck 1997). Precedents do so by defining legal principles that indicate the

relevance or importance of different factual circumstances for a legal dispute and setting

forth legal consequences or tests that follow from particular sets of factual circumstances

(Aldisert 1990; Schauer 1987). For instance, one way precedents matter is by helping judges

compare and group factual circumstances so that similar cases can be treated similarly

(Kornhauser 1989; Lax 2007; Levi 1949; Schauer 1987; Wahlbeck 1997). Precedents are

therefore one of the principal raw materials judges use to decide cases.

The meaning and scope of precedents, and thus their ability to offer this informa-

tional role, are not static but change over time as judges choose whether and how to apply

them in subsequent cases (Gerhardt 2008:200; Hansford & Spriggs 2006:5; Landes &

Posner 1976:250; Merryman 1954:614–16). Legal rules change in part as precedents are

cited by other cases, and when courts reduce or eliminate their use, then those cases’ ability

to structure outcomes and contribute to the law diminishes. As a result, the patterns in case

citations convey important information about the development of the law. Merryman

(1954:615) makes this point when stating that citation choices have “a profound effect on

the way the law grows and the shape legal doctrines take.” Cross et al. (2010:493) articulate

the same idea, maintaining: “An opinion’s citations are the operationalization of the

practice of stare decisis.” Recent research demonstrates that one can use case citations to

measure such concepts as legal change (Hansford & Spriggs 2006), the legal importance of

Supreme Court opinions over time (Fowler et al. 2007; Cross & Spriggs 2010), ideological

bias among judges (Choi & Gulati 2007, 2008), and the ideological location of Supreme

Court precedents (Clark & Lauderdale 2010).

One reason citations have the effect identified by Merryman (1954) and Cross et al.

(2010) is that an important element of stare decisis, analogical reasoning, instructs judges

to use the examples set by prior cases to help decide new disputes and to thus cite cases

based on their legal relevance and authority (Aldisert 1990; Schauer 1987). More specifi-

cally, reasoning by analogy requires judges to compare the factual circumstances in cases

they are deciding with those in past cases and to utilize those precedents that are the most

factually similar to cases being decided. Prior research offers empirical support for this idea,

showing that the Supreme Court is more likely to legally interpret a precedent if it has

greater legal and factual similarity to a case it is deciding, even after accounting for other

important variables related to Court decision making—such as the justices’ ideological

orientations and the legal authority of a precedent (Hansford & Spriggs 2006; Spriggs &

Hansford 2002). Other studies indicate that federal courts are more likely to cite Supreme

Court cases that possess greater legal relevance at a given point in time (Black & Spriggs

2008; Cross et al. 2010; Fowler et al. 2007). In summary, case citations contain information

326 Black and Spriggs

regarding how judges view the relationship of cited cases to the issues in the cases they are

deciding and therefore provide information on the formation and change in the law.

As the current literature stands, it is well established that older cases are generally less

likely to be cited by courts (Black & Spriggs 2008; Cross & Spriggs 2010; Cross et al. 2007;

Fowler et al. 2007; Friedman et al. 1981; Hansford & Spriggs 2006; Landes & Posner 1976,

1980; Merryman 1954, 1977; Spriggs & Hansford 2001, 2002). It is possible, however, that

considerable variation exists regarding which precedents depreciate more quickly than

others. Indeed, there is much speculation that variables such as the generality of a prec-

edent (Landes & Posner 1976), the area of law or the interpretational basis of a case

(Landes & Posner 1976; Gerhardt 2008), the path by which a case develops as evidenced by

its previous citation history (Gerhardt 2008; Meryman 1954:619), the size of the precedent-

setting majority (Cross et al. 2007; Johnson 1987), and the ideology of sitting judges (Cross

et al. 2007) may influence case citations and thus the manner in which a case depreciates.

Although these claims appear regularly in the writings of judges and scholars, no rigorous

empirical test of the way these factors affect the pace of precedent depreciation exists.

This imbalance between an abundance of hypotheses and a lack of empirical evi-

dence serves as the motivation for our article, which asks the following questions: (1) What

is the rate at which U.S. Supreme Court precedents depreciate at the Supreme Court and

courts of appeals? and (2) What factors explain variation in the rate at which cases

depreciate? In what follows, we first describe the existing empirical evidence and then

present a series of hypotheses regarding why some precedents depreciate faster than others.

We then describe our statistical tests, which consist of cross-sectional time-series analyses of

citations to U.S. Supreme Court precedents, released between the 1946 through 2004

terms, by the U.S. Supreme Court and U.S. courts of appeals. Like others (e.g., Landes &

Posner 1976, 1980), we capture the rate of precedent depreciation by estimating the change

in the frequency with which a precedent is cited as a function of it becoming older.

Importantly, we move beyond existing research by determining whether this baseline rate

of depreciation varies by the factors identified in the literature. This formulation allows us

to gauge whether and by how much an independent variable slows or speeds the rate of

depreciation by estimating whether the baseline change in the frequency of citation as a

precedent ages varies across the values of an independent variable of interest.

By way of preview, our results indicate the following:

1. Precedents depreciate rather quickly at the Supreme Court and courts of appeals.

The effect of going from being recently decided to just 10 years of age reduces a

precedent’s value by 65 percent and 72 percent at the Supreme Court and courts

of appeals, respectively. However, the depreciation rate is nonlinear, with younger

precedents depreciating at a much faster rate than their older counterparts. A

10-year increase in age at 40 years of age, for example, yields only an 11 percent

and 30 percent reduction in citation rates at the Supreme Court and courts of

appeals, respectively.

2. Few variables affect the rate of depreciation. Although eight variables and five

variables, respectively, are statistically related to depreciation at the Supreme

Court and courts of appeals, most of these variables’ effects are tiny in magnitude

The Citation and Depreciation of U.S. Supreme Court Precedent 327