American Political Science Review Vol. 103, No. 3 August 2009
doi:10.1017/S0003055409990049
The Constraining Capacity of Legal Doctrine
on the U.S. Supreme Court
BRANDON L. BARTELS George Washington University
D
oes law exhibit a significant constraint on Supreme Court justices’ decisions? Although pro-
ponents of the attitudinal model argue that ideology predominantly influences justices’ choices,
“hybrid models” posit that law and ideology exhibit discrete and concurrent effects on justices’
choices. I offer a new conceptualization of legal constraint examining how legal rules permit varying
degrees of ideological discretion, which establishes how strongly ideological preferences will influence
justices’ votes. In examining the levels-of-scrutiny legal doctrine, I posit theoretical models highlighting
the differential constraining capacities of the strict scrutiny, intermediate scrutiny, and rational basis
rules. I use a multilevel modeling framework to test the hypotheses within the context of the Grayned
doctrine in free expression law. The results show that strict scrutiny, which Grayned applied to content-
based regulations of expression, significantly constrains ideological voting, whereas intermediate scrutiny
(applied to content-neutral regulations) and the low scrutiny categories each promote high levels of
ideological voting.
I
n politics and government, institutions—both rules
and norms—operate as important constraints that
structure the decision-making processes of actors.
Legislators, judges, bureaucrats, voters, and other ac-
tors make decisions within an institutional context de-
fined by formal and informal rules that constrain indi-
vidual discretion and ultimately shape actors’ choices
(e.g., March and Olsen 1984; McCubbins, Noll, and
Weingast 1987; North 1990; Rohde 1991; Shepsle 1979).
On the U.S. Supreme Court, the justices’ institutional
context is almost completely dominated by a web of
informal rules, or norms (e.g., Epstein and Knight 1998;
Maltzman, Spriggs, and Wahlbeck 2000; Murphy 1964).
Perhaps the most important norm on the Court is stare
decisis, or precedent, which is a facet of “the law”
prescribing how past decisions should guide choices
in current and related cases.
1
Supreme Court justices make rules by issuing prece-
dents that contain legal doctrines intended to con-
strain not only lower court judges and actors in the
political environment, but also themselves and future
justices. Legal doctrines, like rules in other contexts,
prescribe certain outcomes under various conditions.
Consequently, legal doctrine is capable of restricting
the range of viable policy alternatives, which serves to
limit individual discretion in decision making by lower
courts and future Supreme Courts (a la McCubbins,
Brandon L. Bartels is Assistant Professor, Department of Political
Science, George Washington University, 2115 G Street, NW, 440
Monroe Hall, Washington, DC 20052 (bartels.20@gmail.com).
A previous version of this article was presented at the 2006
Annual Meeting of the Midwest Political Science Association. I
am extremely grateful to Lawrence Baum for his valuable com-
ments and suggestions at all stages of this project. Thanks also
to Janet Box-Steffensmeier, Roman Ivanchenko, Lindsey Levitan,
Rene Lindstaedt, Kathleen McGraw, Jeffrey Segal, Joel Simmons,
Oleg Smirnov, and Elliot Slotnick for their helpful suggestions. I
thank Mark Richards and Herbert Kritzer for sharing their data.
Finally, I am grateful to the APSR editors and three anonymous
reviewers for extremely valuable feedback and suggestions.
1
In addition to precedent, other facets of the law include plain
meaning and intent underlying the U.S. Constitution and statutes
(see, e.g., Gates and Phelps 1996; Howard and Segal 2002).
Noll, and Weingast 1987). Through this mechanism,
legal doctrine allows the Court to exert control over
the future course of legal policy (Bueno de Mesquita
and Stephenson 2002; Jacobi and Tiller 2007). From a
normative point of view, adherence to precedent sends
a signal to the legal community and the mass public
that the Court’s legal interpretations contain consider-
able continuity and do not change simply because of
membership change on the Court. Such signals, it is
often argued, enhance the legitimacy of the Supreme
Court in the eyes of the public and the other branches
of government (e.g., Epstein and Knight 1998). The
Court’s legal rules also have significant real world im-
plications for rights, liberties, and democracy. Strong
rights-protective rules can be viewed as “democracy
foreclosing” because they restrict the degree to which
elected representatives can make policy on the topic,
whereas more innocuous and minimalistic rules are
“democracy promoting” in that they leave consider-
able room for elected officials to pass laws on the topic
(Sunstein 1999).
In this article, I revisit one of the central inquiries
in judicial politics: how, and to what extent, does le-
gal doctrine genuinely constrain justices’ choices? Al-
though some scholars contend that justices are strongly
guided by legal considerations (e.g., Gilman 1999, 2001;
Kahn 1999), others argue that legal doctrine represents
a flexible norm that has a minimal bearing on the jus-
tices. Proponents of the attitudinal model (Rohde and
Spaeth 1976; Schubert 1974; Segal and Spaeth 2002;
Spaeth and Segal 1999) claim that because Supreme
Court justices are electorally unaccountable and sit
atop the federal judicial hierarchy, they have unbri-
dled discretion to decide cases on the basis of their
ideological, or personal policy, preferences. By ideol-
ogy and policy preferences, which I treat as synony-
mous, I mean that justices are predisposed to hold
views on legal issues that range from liberal posi-
tions to conservative positions. In one test of the legal
model, Spaeth and Segal (1999; Segal and Spaeth 1996)
find that dissenters in landmark cases adhered to
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American Political Science Review Vol. 103, No. 3
precedent in subsequent and related (i.e., progeny)
cases only 12% of the time. They boldly conclude
that “the justices are rarely influenced by stare decisis”
(Spaeth and Segal 1999, 288).
Critics claim that Spaeth and Segal present an anti-
quated “mechanical jurisprudence” perspective of le-
gal reasoning that incorrectly suggests how justices
should automatically adhere to prior controlling prece-
dents (e.g., Friedman 2006; Gilman 2001). Supreme
Court decision making involves greater complexity,
and the effect of the law is often highly nuanced and
difficult to validate with social science research de-
signs. Moreover, the legal doctrines stipulated by the
Supreme Court are not necessarily determinative of
certain outcomes given a configuration of facts (Tiller
and Cross 2006). Instead, they are frameworks that
structure justices’ decision processes (Richards and
Kritzer 2002), and the contextual characteristics of the
case carry considerable sway as well (Winkler 2006).
In addition, although lower court judges are bound
to a greater extent by Supreme Court precedent, the
Supreme Court itself is not explicitly bound to follow
its own precedents. However, there are several rea-
sons why the justices would want to be faithful to and
constrained by the Court’s own precedents. First, jus-
tices are socialized to be accountable to the body of
law that has preceded them. Justices are, at the least,
sensitive to the norm of respect for past precedents
and legal frameworks (e.g., Baum 2006; Braman 2004;
Knight and Epstein 1996). They are also accountable
to the legal audiences—other judges, lawyers, the me-
dia, the intellectual community—who comment on and
interpret justices’ decisions (see Baum 2006). Second,
although ideological motivations might lead the Court
to create certain legal doctrines, once they are created,
it is often in the Court’s interests to abide by them
in order to impose stability and predictability within
the legal system (Bueno de Mesquita and Stephenson
2002; Richards and Kritzer 2002). The Supreme Court
sits at the apex of an extensive federal judicial hier-
archy. Therefore, it is charged with the responsibility
of providing guidance and clear signals to lower court
judges and lawyers about how its doctrines should be
interpreted. Efficient management of the lower courts
and an instinct to maintain its institutional legitimacy
prevents the Court from producing frequent, wholesale
reversals of its precedents.
Adopting some of these arguments in response to
the attitudinal model, alternative perspectives contend
that although ideology influences justices’ choices, the
law exerts an independent and concurrent influence
as well (e.g., Bailey and Maltzman 2008; Baum 1997;
George and Epstein 1992; Pritchett 1954; Richards
and Kritzer 2002). I refer to such models as “hybrid
models,” and one of the most influential is Richards
and Kritzer’s (2002) “jurisprudential regimes theory,”
which posits that certain precedents create jurispru-
dential regimes—essentially legal doctrines created by
the justices to structure future decision making—high-
lighting how legal standards should apply to certain
types of fact situations. In sum, although hybrid mod-
els argue for a genuine influence of the law, they also
concede that ideology exhibits an impact on decision
making that is independent from the law. That is, they
focus on the discrete channels of influence exhibited by
law and ideology, which I argue leaves a significant gap
in our understanding of precisely how legal doctrine
constrains justices. Moreover, these perspectives do not
place an explicit emphasis on the differential impacts
of legal rules.
In this article, I offer a new perspective on how and
to what extent law constrains justices’ decision mak-
ing. I provide two central contributions. First, although
hybrid models highlight the discrete and orthogonal ef-
fects of law and ideology, I offer a theoretical departure
from hybrid models and posit how legal rules permit
varying degrees of ideological discretion justices have
in a given case, which in turn shapes the magnitude of
ideological voting (i.e., the degree to which ideology in-
fluences justices’ choices). I present competing models
of how the levels-of-scrutiny legal doctrine—employed
for numerous legal issues—shapes ideological discre-
tion among the justices.
The article’s second key contribution centers on the
notion that not all rules emanating from a legal doc-
trine carry with them the same constraining capacity.
Political scientists often think of rules as necessarily
limiting an actor’s discretion; the same logic is often ap-
plied to legal doctrine on courts. However, my theoret-
ical framework specifically highlights how some rules
significantly constrain ideological discretion, whereas
others give justices a significant amount of discretion
to act on the basis of ideological preferences. I test these
propositions using cases from free expression law. The
theory and findings provide a compelling and more
complete portrait of law’s influence in Supreme Court
decision making, focusing on the mechanisms under-
lying the constraining—and nonconstraining—capacity
of legal rules on the Supreme Court.
THE CONSTRAINING CAPACITY OF
LEGAL DOCTRINE: A NEW PERSPECTIVE
I begin this section by explaining the function of a
widely used legal doctrine on the Supreme Court: the
levels-of-scrutiny framework. I then present compet-
ing models for how the rules within this framework
constrain or do not constrain ideological discretion.
The Levels-of-Scrutiny Doctrine
In setting legal doctrine, the Supreme Court prescribes
different levels of scrutiny to various types of gov-
ernmental laws and regulations. In constitutional law,
these levels of scrutiny reflect the Court’s interpreta-
tion of how protective the Constitution should be of
rights and liberties, such as equality, the right to pri-
vacy, and the freedoms of speech, press, and religious
exercise. Higher levels of scrutiny are highly rights pro-
tective and coincide with a strong presumption that a
rights-restrictive government act will be struck down by
the Court as a violation of the Constitution. By a “gov-
ernment act,” I mean either a law passed by a federal,
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Constraining Capacity of Legal Doctrine August 2009
state, or local government or an action of a government
official. Lower levels of scrutiny reflect a lower degree
of rights protectiveness and presume that a govern-
ment act is valid. Where do these rules come from?
Although one could argue that the Supreme Court has
always used the logic underlying levels of scrutiny when
deciding whether the Constitution should invalidate
a government act, the Court first formalized such a
framework in the “famous footnote 4” in U.S. v. Car-
olene Products (1938) (Chemerinsky 2002; Tribe 1988;
Winkler 2006). In the footnote, Justice Stone argued
that governmental regulations of the economy should
receive low judicial scrutiny and should therefore pos-
sess presumptive validity. However, Stone argued that
government acts placing restrictions on fundamental
constitutional rights and liberties (e.g., freedom of
speech, press) should receive greater judicial scrutiny.
In the development of constitutional law in vari-
ous issue areas, three legal rules have emanated from
this doctrine (see Winkler 2006). Each suggests dif-
ferent standards of balancing individual rights and
liberties versus governmental interests.
2
The first is
strict scrutiny, which is the most rights-protective
level of review and places the burden of proof
on the government to demonstrate a compelling
state interest for the existence of a rights-restrictive
government act. Under strict scrutiny, there is a
presumption that such an act will be struck down—
unless it is narrowly tailored to achieve a compelling
state interest—because it violates a right or liberty
deemed to be fundamentally protected by the U.S.
Constitution. It is often said that this rule is “‘strict’
in theory and fatal in fact” because a law accorded
strict scrutiny will hardly ever pass the very high bar
that constitutes a “compelling state interest” (Gunther
1971, 8; Winkler 2006). However, Winkler (2006, 796)
finds that a nontrivial proportion of federal court cases
has been upheld under strict scrutiny review, suggest-
ing that strict scrutiny is “survivable in fact” (see also
Baldez, Epstein, and Martin 2006). In equal protec-
tion law, at least since Brown v. Board of Education
(1954), laws discriminating on the basis of race are ac-
corded strict scrutiny. For free expression, government
acts that regulate the content of speech (i.e., content-
based regulations) have traditionally been accorded
strict scrutiny (Richards and Kritzer 2002). In Roe v.
Wade (1973), the Court prescribed strict scrutiny to
laws regulating abortion during the first two trimesters
(the previability stage) of pregnancy.
The second and least rights-protective rule is rational
basis, which places the burden of proof on the individ-
ual challenging a government act to show that one’s
individual rights and liberties have been significantly
infringed upon. This standard of review grants the gov-
ernment the maximum amount of latitude in making
2
Legal scholars often differentiate between “rules” and “standards”
(Jacobi and Tiller 2007; Tiller and Cross 2006). Rules are generally
determinative of a particular outcome, whereas standards provide a
less determinative guide for making a decision. Although levels of
scrutiny are standards, I use the term “rules” to describe them here
because it is in accord with my focus within political science on how
institutions influence government actors.
rights-restrictive restrictions that serve a legitimate or
reasonable purpose. In rational basis review, the Court
presumes a government act will be upheld. In Roe v.
Wade (1973), the Court assigned rational basis review
to laws regulating abortion during the third trimester of
pregnancy. The Court argued that during this advanced
stage of pregnancy, a government has a legitimate inter-
est in protecting a fetus that could survive outside the
womb. In free expression law, traditionally less pro-
tected forms of speech, such as obscenity (Miller v.
California 1973) and “fighting words” that could incite
violence (Chaplinski v. New Hampshire 1942), have
been given the lowest amount of scrutiny, and there-
fore, the lowest amount of constitutional protection
(Richards and Kritzer 2002).
In between these two levels of scrutiny falls the
third rule: intermediate scrutiny. For this rule, which
is moderately rights protective, a government act will
be upheld if it is “substantially related to an important
government interest” (Chemerinsky 2002, 519). For in-
termediate scrutiny, the government bears a fraction
of the burden of proof to demonstrate why it passed a
particular rights-restrictive law, but the individual also
bears a fraction of this burden to demonstrate that
the law violates a fundamental constitutional freedom.
Importantly, there is no presumption for whether a
government act accorded this level of review should
be upheld or struck down. In the Court’s Planned
Parenthood v. Casey (1992) decision, which amended
the Roe v. Wade doctrine, the Court prescribed that
governmental regulations of previability abortions be
accorded a form of intermediate scrutiny known as the
“undue burden” test. By lowering the standard from
strict to intermediate scrutiny, the Court gives states
more discretion to place certain restrictions on abor-
tion, yet it still suggests a constitutional threshold that
states cannot exceed. In free expression law, content-
neutral regulations—those not based on content but
on time, place, and manner restrictions—have been
accorded intermediate scrutiny (Richards and Kritzer
2002). In equal protection issues, laws discriminating
on the basis of sex are accorded intermediate scrutiny
(Craig v. Boren 1976), which gives government some
latitude to legislate sex classifications (see also Baldez,
Epstein, and Martin, 2006).
Levels of Scrutiny and Ideological
Discretion: Competing Theoretical Models
I contend that the rules within the levels-of-scrutiny
framework permit varying degrees of discretion jus-
tices have to decide the case on the basis of their
ideological preferences. They do so by restricting or
expanding the set of feasible outcomes available to the
justices. Here, I present competing models of this pro-
cess. Importantly, the models highlight the differential
constraining capacities of legal rules. Figure 1 aids in
the discussion of the models.
I refer to the first model as the “legal presump-
tions” model, which emphasizes that constraint is a
function of how strongly a legal rule presumes a cer-
tain case outcome. For the strict scrutiny and rational
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American Political Science Review Vol. 103, No. 3
FIGURE 1. Constraining Capacity of Legal Rules: (A) Legal Presumptions Model,
and (B) Rights-Protectiveness Model
A
B
Degree of Ideological
Discretion
Level of Scrutiny
Rational Basis Intermediate Strict
High
Low
Level of Scrutiny
Rational Basis Intermediate Strict
High
Low
Degree of Ideological
Discretion
basis rules, the strong presumptions of striking and
upholding a rights-restrictive regulation, respectively,
means that justices have fewer legally justifiable alter-
natives available to them compared to a case where
there is no presumptive outcome, as in intermediate
scrutiny. Thus, where the presumption of a certain out-
come is high, the legal rule stipulates a particular out-
come and therefore leaves a low degree of discretion
for ideologically driven behavior. However, for inter-
mediate scrutiny, where no presumption exists, justices
possess a considerably higher degree of ideological dis-
cretion (compared to strict scrutiny and rational basis),
where they can more freely decide cases on the basis
of their ideological preferences.
It is important to note here that even though rational
basis does not always lead to a justice to cast a pro-
government (conservative) vote and strict scrutiny
does not always lead a justice to cast a proindividual
(liberal) vote (e.g., Baldez, Epstein, and Martin, 2006;
Winkler 2006), each rule can still constrain ideological
discretion. Indeed, one would not expect judges, es-
pecially Supreme Court justices, to cast votes in ac-
cord with a legal presumption 100% of the time. Other
contextual characteristics of the case come into play,
and, as Winkler (2006) shows, strict scrutiny is indeed
“survivable in fact,” with judges sometimes able to
find a compelling state interest that justifies a rights-
restrictive regulation. Given this, though, legal pre-
sumptions can still exhibit constraint on individual
discretion because they restrict the range of legally jus-
tifiable conclusions for ruling against the presumption.
However, for intermediate scrutiny, where the range
of viable alternatives is greater because of the lack of
a legal presumption, judges have a greater ability to
decide the case on the basis of ideological preferences.
Figure 1A depicts the “legal presumptions model.”
The x-axis represents the three levels of scrutiny, rang-
ing from rational basis to strict scrutiny. The y-axis rep-
resents the amount of ideological discretion justices
have in a given case. The legal presumptions model
477
Constraining Capacity of Legal Doctrine August 2009
posits that ideological discretion is a nonlinear func-
tion of the levels of scrutiny. This model implies that
for rational basis and strict scrutiny, where there is a
strong presumption for a particular outcome, ideologi-
cal discretion is low. But for cases involving intermedi-
ate scrutiny, discretion is quite high. For strict scrutiny,
rights-protective standards are maximized, and there
is a presumption that the rights-restrictive regulation
should be struck down. Thus, if strict scrutiny operates
as a constraint, it significantly limits a justice’s freedom
to reach a conclusion that the act should be upheld.
For rational basis, if a strong norm of deference toward
the government is operative, which presumes a gov-
ernment act should be upheld, it significantly limits a
justice’s freedom to reach the conclusion that the act
should be struck down. For intermediate scrutiny, the
model posits that ideological discretion is maximized
relative to the other two rules because there is no strong
presumption about the fate of a government act.
Thus, the expectation from the legal presumptions
model is that the impact of ideological preferences
on justices’ choices will be significantly higher for in-
termediate scrutiny compared to both rational basis
and strict scrutiny. Importantly, the model highlights
the differential capacities of legal rules to exhibit con-
straint. Rules that presume the validity or invalidity of
a government act are posited to significantly constrain
ideological discretion. But intermediate scrutiny, which
does not presume an outcome, will not constrain jus-
tices, therefore leaving them wide-ranging discretion
to pursue ideological preferences.
Unlike the legal presumptions model, the “rights-
protectiveness model” posits that it is not the presump-
tion of an outcome, per se, that constrains justices,
but the degree to which a doctrine deems that the
Constitution is protective of rights and liberties. Put
another way, legal rules that prescribe greater consti-
tutional scrutiny of a law will exhibit more constraint
on ideological discretion compared to rules that pre-
scribe lower scrutiny. Figure 1B depicts this logic, where
ideological discretion is a linear function of scrutiny.
For strict scrutiny, ideological discretion is minimized
because legal doctrine stipulates that the Constitution
is explicitly prescribing a certain outcome (i.e., strik-
ing down a rights-restrictive government act). As the
level of scrutiny decreases (from intermediate scrutiny
to rational basis), ideological discretion increases. In
this model, it is the degree to which the Constitution
protects a right or liberty that constrains justices. The
rational basis rule suggests that the Constitution is
not significantly rights protective for a class of rights-
restrictive government acts, and therefore, the doc-
trine does not impose any constitutional constraint on
ideological discretion. Intermediate scrutiny suggests
greater rights protectiveness than rational basis but less
than strict scrutiny. Therefore, this rule should impose
moderate constraint on ideological discretion.
The rights-protectiveness model’s expectation for
the rational basis rule accords with classic behavioral
studies (e.g., Spaeth 1964; Spaeth and Teger 1982)
in suggesting that a deference norm toward the gov-
ernment is not operative on the Court. The legal
presumptions model rests on the assumption that, un-
der rational basis review, the Court will defer to the
government via a presumption to uphold the law.
The rights protectiveness model, however, suggests
that the Court will not defer to a government under
rational basis because the Court is only constrained
by the degree of constitutional scrutiny given to a class
of cases; rational basis review is associated with a very
low degree of constitutional scrutiny. Under this model,
the Court is only responsive to, and constrained by, high
levels of constitutional scrutiny in conjunction with the
intent of the Constitution. The First Amendment states
that “Congress shall make no law...abridging the free-
dom of speech....” The Court has used doctrine to fill
in the gaps of this language, but the Constitution is clear
about protecting the freedom of speech against gov-
ernment restrictions. However, it is not explicit about
when the government should receive deference when
passing rights-restrictive laws. Thus, this model posits
that the more explicitly the Constitution speaks toward
a particular law, the less ideological discretion justices
will have.
In sum, the expectation from the rights-protec-
tiveness model is that ideological discretion will be
higher for rational basis than for intermediate scrutiny,
and discretion for intermediate scrutiny will in turn be
higher than for strict scrutiny. Like the previous model,
the rights-protectiveness model highlights the differ-
ential constraining capacities of legal rules. Here, rules
that prescribe greater constitutional scrutiny will con-
strain ideological discretion. But rules that prescribe
low constitutional scrutiny will not constrain justices,
leaving them significant discretion to act on the basis
of their ideological preferences.
FREE EXPRESSION LAW
To test these competing theoretical models, I analyze
Supreme Court justices’ behavior in cases from the
free expression issue area, which includes freedom of
speech and press issues. This issue area presents a clean
test of the perspective presented previously. Through
a qualitiative and quantitative assessment, Richards
and Kritzer (2002) argue that two 1972 Supreme
Court cases, Chicago Police Department v. Mosley and
Grayned v. Rockford, instituted a legal doctrine (here-
inafter, the “Grayned doctrine”) prescribing levels of
scrutiny that should be applied to four different types
of governmental regulations of expression. Richards
and Kritzer found empirical support for their theory
that jurisprudential regimes structure justices’ decision
making.
The key difference between my theoretical per-
spective and Richards and Kritzer’s is that they fo-
cus on how the probability of justices’ proexpression
voting differs between the four legal categories, and
whether these differences are distinct after Grayned
compared to before. The theoretical propositions I
have posited entail comparing the impact of ideology
on vote choices among these legal categories as a re-
sult of the Grayned doctrine. As discussed previously,
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