Legislators and executives campaign explicitly on their political beliefs, and once elected they are expected to make decisions based on these beliefs. These decisions may stem from the candidate’s own moral values, or a cost/benefit analysis of the possible solutions to a problem, or simply what seems to be best for the state or the country. But the judicial branch is supposed to be above politics: judges are meant to decide cases based on neutral legal principles, not their own personal ideology, or not even what is best for the citizens. To a great extent, of course, this characterization of judges is true: when a judge decides a case, he or she must be guided by the law set out by the other two branches, or by the Constitution. In their decisions, judges frequently point out that they are not passing judgment on the wisdom of the law they are enforcing—they are only interpreting the law, or ensuring that the law is consistent with the Constitution or other superseding legal authority.

But as everyone knows, the truth is a bit more complicated. Nobody truly thinks of judges as completely beyond politics—it is common to speak of a “liberal” judge or a “conservative” judge. Every time the President nominates a new Supreme Court Justice, the Senate and the country as a whole eagerly pore over the nominee’s prior judicial record and writings, trying to discern the political leanings of the potential Justice in an attempt to predict how he or she may rule on the significant legal disputes of the day. Elections for state Supreme Court justices frequently turn on blatantly political issues, and even trial court judges who set bail and make sentencing decisions are viewed through a political prism as being “soft” or “tough” on crime.

This dissonance between the theory of a neutral, non-partisan judge and the reality of a judge who has a political affiliation creates a serious problem. The problem is, at its core, one of terminology. When people attempt to apply political labels to judges, they invariably create confusion, because the labels were developed to apply to true politicians, not judicial officers. What, for example, is a “conservative” judge? Someone who votes that anti-abortion laws are constitutional? Someone who narrowly interprets an affirmative action law? Someone who imposes (or upholds) long prison sentences for convicted criminals? Although in the political realm, these three positions are linked as “conservative” positions, there is nothing to link them together in the judicial world—that is, there is really no reason to believe that a judge who supports one of these positions will support either of the other two.

To make matters worse, the judicial realm has its own unique additions to the concepts of what is conservative or liberal: Is the judge a “strict constructionist” who refuses to examine legislative history or consider policy arguments when interpreting a statute? Does the judge show judicial restraint and defer to the other two branches of government when reviewing a statute or regulation? These two judicial philosophies are thought to be “conservative,” but they bear no relationship to what we think of as politically “conservative:” for example, a judge who exercises “judicial restraint” should apply that philosophy to anti-abortion laws and to affirmative action laws, preferring to let them both stand in the face of a Constitutional challenge. (See Glossary of Judicial Philosophies for further discussion of what these principles actually mean.

Political scientists have been intrigued by this question for decades, and they have conducted hundreds of surveys and written dozens of articles attempting to translate judges’ decisions into familiar political categories. These scholars also take a further step, attempting to find correlations between voting patterns and other variables, such as the political affiliation of the President who nominated them, or the personal or professional backgrounds of the judges. Below is a very brief summary of this scholarship.

Classifying judicial decisions as “liberal” or “conservative”

Most studies of judicial decisionmaking use a relatively simple view of “liberal” or “conservative,” as described by Professor Daniel R. Pinello in a recent article:

“Scholars have used consistent definitions of liberal and conservative judicial action. In criminal justice cases, votes favoring the defendant are liberal; those for the prosecution, conservative. In government regulation of the economy, choosing the regulator is liberal; the regulated, conservative. Preferring workers in labor regulation cases is liberal; employers, conservative. In civil rights and liberties, votes for the claimed right are liberal; against the right, conservative.”

These broad categories probably fit the general political conception of “political” and “conservative” rather well, though they leave out some significant “culture war” issues, such as abortion, gay rights, or gun rights. But of course the more detailed the analysis, the more choices the analyst must make about whether each type of decision is liberal or conservative. By far the most prominent (and comprehensive) database of Supreme Court decisions is the Spaeth Database, created by Howard Spaeth, a political science professor at Michigan State University. ( The database categorizes legal issues into thirteen different major categories (which he also subdivides into hundreds of minor categories):

1 Criminal procedure
2 Civil Rights
3 First Amendment
4 Due Process
5 Privacy
6 Attorneys
7 Unions
8 Economic activity
9 Judical power
10 Federalsim
11 Interstate relations
12 Federal taxation
13 Miscellaneous

The database then classifies each of the sub-categories of these issues as “conservative” or “liberal,” though it admits that “[c]ounting such cases is a matter of judgment.”2 The classifications are as follows:
In the context of issues pertaining to criminal procedure, civil rights, First Amendment, due process, privacy, and attorneys:

Liberal=

pro-person accused or convicted of crime, or denied a jury trial
pro-civil liberties or civil rights claimant, especially those exercising less protected civil rights (e.g., homosexuality)
pro-child or juvenile
pro-indigent
pro-Indian
pro-affirmative action
pro-neutrality in religion cases
pro-female in abortion
pro-underdog
anti-government in the context of due process, except for takings clause cases where a pro-government, anti-owner vote is considered liberal except in criminal forfeiture cases or those where the taking is pro-business
violation of due process by exercising jurisdiction over nonresidents
pro-attorney pro-accountability and/or anti-corruption in campaign spending
pro-privacy vis-a-vis the 1st Amendment where the privacy invaded is that of mental incompetent
pro-jurisdiction and pro-disclosure except for employment and student records

Conservative = reverse of above

In the context of issues pertaining to unions and economic activity:

Liberal =

pro-union except in union antitrust [which is conservative]
anti-business
anti-employer
pro-competition
pro-liability
pro-injured person
pro-indigent
pro-small business vis-a-vis large business
pro-debtor
pro-bankrupt
pro-Indian
pro-environmental protection
pro-economic underdog
pro-consumer
pro-accountability in governmental corruption
anti-union member or employee vis-a-vis union
anti-union in union antitrust
pro-trial in arbitration

Conservative = reverse of above

In the context of issues pertaining to judicial power:

Liberal =
pro-exercise of judicial power
pro-judicial “activism”
pro-judicial review of administrative action

Conservative = reverse of above

In the context of issues pertaining to federalism

Liberal =
pro-federal power
anti-state

Conservative = reverse of above
In the context of issues pertaining to federal taxation

Liberal = pro-United States

Conservative = pro-taxpayer

Few people would argue with most of these judgment calls, though they are not foolproof. Some of the judgments still paint with a rather broad brush (“pro-liability” in all cases pertaining to “economic activity,” for example, or “pro-federal power” in every case involving federalism). Others require quite a bit of interpretation on the part of the individual coding the decisions—for example, what types of cases are “pro-underdog” or “pro-economic underdog?” Still others require an interpretation of complicated concepts: “pro-judicial ‘activism’” for example—many people may disagree as to what constitures “judicial activism.” Finally, some of the categories depend on how you define “conservative” and “liberal”—for example, would a liberal always be pro-neutrality in religion cases? Or would a liberal always be pro-competition in economic activity cases?

Studies using the Spaeth database are quite common. The database was the basis for a front page article in the July 25, 2010 New York Times article describing how the United States Supreme Court has shifted to the right over the past few decades, and is now the “most conservative court in decades.” The Spaeth database was also the basis for a landmark article by William M. Landes and Richard A. Posner in 2009 which ranked the most recent forty-three Supreme Court Justices from most conservative to most liberal and concluded that four of the top five conservative Justices over the past sixty-three years are currently sitting on the court.

Another database which classifies decisions (and the judges who issue the decisions) as liberal or conservative is the Songer database for federal appeals court judges. The Songer database recognizes that “some issues are not easily categorized along a liberal/conservative dimension” and that “some users may want to define liberal and conservative in at least partially different ways.” In the end, the Songer database makes many of the same choices as the Spaeth database in categorizing a decision as conservative or liberal.

A different study by Adam Bonica of Stanford and Micheal J. Woodruff of NYU uses campaign finance records to measure the political leanings of state supreme courts. Bonica and Woordruff study the relationship between judicial selection methods and the quality of ideological representation in the state courts, and conclude that “judicial elections can lead to more representative courts but that the beneficial effects are negated by policies intended to promote judicial impartiality by limiting the politicizing effects of partisan affiliation and campaign speech.”

Finally, a mention should be made of the State Supreme Court Data Project, a comprehensive database of state court decisions over the past few decades. This project categorizes state supreme court decisions by parties involved and legal issues involved, but it does not attempt to classify decisions as “liberal” or “conservative.

Results of studies

Based on data such as those collected in the Spaeth and Songer databases, legal and political science scholars have conducted hundreds of studies on the voting behavior of judges. One meta-analysis of these studies concluded that judges appointed by Republicans tended to vote more conservatively than judges appointed by Democrats. The aforementioned study by Landes and Posner also confirmed this rather uncontroversial finding. In fact, the party affiliation of the appointer was the strongest indicator of all the factors in determining whether a judge would vote as a “liberal” or a “conservative” in non-unanimous cases.

But as might be expected, the complete picture is a bit more complicated. A study of appellate court judges in the early 1960’s found that the correlation between the appointing President’s ideology and judicial decisionmaking was strong for economic issues but negligible for criminal and civil liberties issues. However, when the study was repeated for the next five-year period, the correlation was at least as strong for criminal and civil liberties issues as it was for other types of cases. Part of the difference could be explained by a difference in the methodology between the two studies, but the author of both studies also noted the late 1960s was a time when political liberties issues and criminal justice issues became politicized—and that this shift was reflected in the judges appointed during that time. A different article that looks at conclusions of hundreds of judicial studies meta-analysis shows a very high correlation between the appointer’s political affiliation and judicial decisions in civil rights and criminal justice cases—much higher than for other issues. Meanwhile, studies of trial court judges, who are bound much more rigidly by the law of any particular case, find little or no correlation between political affiliation and judicial decisions.

In short, although a correlation has been found between the political party of the appointer and the direction of the judge’s decisions, there was quite a bit of variability for different specific issues. As another scholar noted, classifying a judge by ideology or political party is misleading, because “it divides [judges] into only two–or perhaps three–large, undifferentiated groups….” If a President were trying to decide whether to appoint a candidate to a judgeship, for example, he or she would do more than simply check the party affiliation of the candidate. The President may want to “pursue a particular ideological agenda typically involv[ing] a certain type of liberalism or conservativism as well as positions on specific legal issues such as abortion, civil rights, and criminal procedure”—and party affiliation is not a sufficient indicator to predict with confidence how a judicial candidate will vote on any given issue. The same principle holds true for voters in judicial elections—although party affiliation is a strong indicator, it is important to delve a little deeper into each candidates’ views before casting a vote.