Birth Order, Preferences, and Norms on the U.S. Supreme Court

• Published date: 01 December 2015
• DOI: http://doi.org/10.1111/lasr.12169
• Date: 01 December 2015

Birth Order, Preferences, and Norms on the U.S.

Supreme Court

Kevin T. McGuire

The members of the U.S. Supreme Court have different ideas about what

constitutes good judicial policy as well as how best to achieve that policy. From

where do these ideas originate? Evolutionary psychology suggests that an

answer may lie in early life experiences in which siblings assume roles that

affect an adult’s likely acceptance of changes in the established order.Accord-

ing to this view, older siblings take on responsibilities that make them more

conservative and rule-bound, while younger ones adopt roles that promote

liberalism and greater rebelliousness. Applying this theory to the Court, I

show that these childhood roles manifest themselves in later life in the deci-

sions of the justices. Birth order explains not only the justices’ policy preferen-

ces but also their acceptance of one important norm of judicial

decisionmaking, specifically their willingness to exercise judicial review.

The principles of the American legal tradition are thought to

place limits on the members of the U.S. Supreme Court. Fidelity to

written law, support for the doctrine of stare decisis, and deference

to elected majorities are among the standard elements of the judicial

canon. It is clear, however, that the justices make decisions with an

eye toward achieving their policy goals and that they vary consider-

ably in the extent to which they support judicial norms in their reso-

lution of cases. How do the justices form their ideas about what

constitutes good judicial policy and how judges should achieve it?

One plausible explanation, drawn from the field of evolution-

ary psychology, suggests that a process of socialization determines

one’s attitudes toward norms, rules, and authority (Buss 1997).

This socialization takes place long before assuming adult roles,

such as judging. Indeed, it occurs during childhood, governed by

an individual’s relative position among siblings. Birth order has

I am grateful for the insights and suggestions of John Aldrich, Roy Flemming, Tracey

George, William Jacoby,Michael Mackuen, Georg Vanberg, the anonymous reviewers, and

the participants in the visiting speaker series at the Rooney Center for the Study of Ameri-

can Democracy at the University of Notre Dame.

Please direct all correspondence to Kevin T. McGuire, Department of Political Science,

University of North Carolina at Chapel Hill, CB# 3265, 353 Hamilton Hall, Chapel Hill,

NC 27599; e-mail: kmcguire@unc.edu.

Law & Society Review, Volume 49, Number 4 (2015)

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C2015 Law and Society Association. All rights reserved.

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long been a subject of intensive study, and in recent years

researchers have given close attention to its linkage to a person’s

receptivity to change. Specifically, evolutionary psychologists posit

that, early in life, individuals engage in adaptive behaviors that

are conditioned by the presence of siblings and seek certain

niches that maximize parental attention (Sulloway 1996). Older

siblings—firstborns in particular—are thought to identify with

and emulate their parents and are thereby rewarded for their

conscientiousness and respect for authority. As a consequence of

these behavioral adaptations, firstborns develop not only ideologi-

cally conservative preferences but also a tendency to reject intel-

lectual innovation, owing to their strong inclination to support

the status quo. Laterborns, by contrast, must be creative and

adaptable as a means of distinguishing themselves from their

older siblings. Because of their openness to novel ideas, later-

borns acquire more liberal political preferences as well as a pre-

disposition to take risks and to rebel against convention.

Applying the birth order thesis to the U.S. Supreme Court, I

argue that the justices’ microenvironments during childhood should

affect their approach to legal decisionmaking on the bench. First,

birth order should explain the justices’ ideological orientations;

older siblings on the Court should have more conservative prefer-

ences; younger siblings, more liberal attitudes. Second, the impact

of birth order should also be revealedinthejustices’roleorienta-

tions. Owing to their deference to authority, firstborn justices

should support existing regimes, defer to popular decision makers,

and exercise restraint. Laterborn justices, by contrast, should evince

activism; being less tethered to the status quo, such justices should

be more open to questioning the judgments of elected officials.

Testing this theory, I find clear support for birth order effects. The

evidence reveals that birth order is directly linked to the justices’

preferences. Likewise, birth order helps to account for their deci-

sions about how to realize their policy goals; although ideology gov-

erns how the justices view the constitutionality of challenged

legislation, birth order conditions the justices’ willingness to strike

down the actions of popular decision makers.

In the following sections, I sketch the psychological theory

about the importance of birth order, and I derive hypotheses about

its relevance to the justices’ policy attitudes and their approaches to

judging. I then subject those hypotheses to statistical test.

Birth Order and the Niche-Seeking Hypothesis

Analyses of judicial behavior and theories of psychology have

increasingly important intersections (Klein and Mitchell 2010),

946 Birth Order, Preferences, and Norms