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

Published date01 December 2015
Date01 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:
Law & Society Review, Volume 49, Number 4 (2015)
C2015 Law and Society Association. All rights reserved.
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

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