An Introduction to Empirical Legal Research

398 Pages·2014·5.21 MB·English

by  Lee Epstein & Andrew D. Martin

An Introduction to Empirical Legal Research
An Introduction
to Empirical Legal
Research
Lee Epstein
Washington University in St. Louis
Andrew D. Martin
University of Michigan
Great Clarendon Street, Oxford, OX2 6DP,
United Kingdom
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To an empirical scholar extraordinaire (and one of my favorite people in the
whole wide world), Jeffrey A. Segal.—L.E.
To Stephanie and Olive, the two most important people in my life.
—A.D.M.
Preface
To claim that research based on data—that is, empirical work—has infiltrated
the legal community borders on the boring.1 Social scientists and historians have
long brought data to bear on the study of law and legal institutions.2 In ever-
increasing numbers, legal academics throughout the world are following suit.3
But it’s not only academics who are making greater use of data-based
evidence in their research. Arguments following from empirical studies have
become such a regular part of legal practice that lawyers (and law students!)
neglect learning about methods for collecting and analyzing data at their own
peril. We could say the same of judges who are all too often confronted with
data or the results of empirical studies in cases ranging from bankruptcy to
criminal law to environmental infringement to taxation.4 As Oliver Wendell
Holmes famously wrote, “For the rational study of the law the black letter man
may be the man of the present, but the man of the future is the man of statistics
and the master of economics.” 5 That future is here.6
And yet there is no book designed to provide members of the legal
community with a sufficient introduction to empirical legal work so that they can
evaluate existing studies, become conversant in basic statistical methods, begin
to undertake investigations of their own, or all of the above.7 Hence An
Introduction to Empirical Legal Research— a book explicitly for law students,
lawyers, judges, and scholars interested in law and legal institutions.
In producing An Introduction to Empirical Legal Research we drew heavily
on materials we developed for an annual empirical workshop for law professors,
courses we offer to law students, and a day-long educational program for judges.
We also made liberal use of the handful of articles we have written on designing,
executing, and presenting the results of statistical studies.8
Throughout our courses and articles we bring in many practical examples.
Some are of our own devising, others come from existing empirical studies, and
still others from court cases. No matter the source, we go beyond mere
description; we make use of data so that our students and readers can experience
the research process for themselves. This is extremely important here too.
Regardless of whether you are reading An Introduction to Empirical Legal
Research to consume or produce empirical studies, only by understanding the
process will you be able to decipher its products—including scholarly articles,
consultants’ reports, and expert testimony9
For readers hoping to learn enough about these products so that they can
follow and evaluate them, working through the examples in the book may be
suficient. For those desiring to execute empirical studies, the book’s website
houses the tools necessary to replicate and expand the examples in the book.10 In
particular, you’ll find:
Datasets. For each dataset we use in the book, we’ve created a comprehensive
codebook and a downloadable data file in various formats (comma delimited
text, Stata, SPSS Portable, R Data Format, SAS Transport, and Microsoft
Excel).
Introduction to Statistical Software. We provide introductions to two different
packages: Stata11 and R.12 The introductions include step-by-step written
documentation and video demonstrations of both packages.
Chapter-by-Chapter Command Files. Along with the datasets, the command
files enable the reader to replicate (in Stata or R) every analysis in the book.
“Best Practices” Guide. This guide should help ensure that research employing
R or Stata not only makes effective use of the software but also conforms to
standard operating procedures in the field.
References. The website provides a list of some of our favorite books on
research design, data collection methods, and statistics. It also includes links
to datasets that you might find useful for law-related projects.
One final note. It’s important to keep in mind the first two words of the book’s
title. We do indeed conceptualize An Introduction to Empirical Legal Research
as a primer. Mastering all the topics we cover requires far more than we can
possibly convey here; it requires training. That’s why Ph.D. programs in the
social sciences not only offer basic introductions to research design and statistics
but also courses devoted to particular types of methods—maximum likelihood
estimation, time series analysis, and structural equation models, to name just a
few. Our goal is to provide readers with a sufficient foundation to read and
evaluate empirical work and, if they so desire, to begin to design studies of their
own. After attending our workshops, many participants (students and faculty
alike) delved further into the subjects we covered and, ultimately, went on to
produce high-quality empirical studies. We hope An Introduction to Empirical
Legal Research encourages a similar investment of time with equally good
results.
Let’s get started.
L.E.
St. Louis, Missouri, USA
A.D.M.
Ann Arbor, Michigan, USA
1
In Chapter 1, we flesh out the meaning of “empirical work.” Suffice it to note here that data in
empirical studies come in two flavors: quantitative (numerical) and qualitative (non-numerical). Neither is
any more “empirical” than the other (see Epstein and King, 2002).
2
Though certainly not as long as in the sciences. Stigler (1986, 2) puzzles over why “it is only in the
twentieth century that [statistical methods made] substantial inroads into the social sciences. Were
nineteenth-century social scientists unable to read?”
3
For documentation of the increasing use of data in law reviews and journals, see George (2005). She
contends that “Empirical legal scholarship is arguably that next big thing in legal intellectual thought” (p.
141). But she also notes that “empirical research in law is not new” (see also Kritzer, 2009; Schlegel, 1995).
This is certainly true in the United States where several early empirical studies have attained landmark
status, including Clark and Shulman (1937); Frankfurter and Landis (1928); Kalven and Zeisel (1966);
Landes and Posner (1976). Though data work was slower to catch on in other corners of the world, no
longer is “a lively interest in empirical legal research … confined to the United States and the UK;” there
are “active communities of empirical legal researchers” in Australia, Canada, the Netherlands, Belgium,
Spain, Germany, Israel, and Japan (Cane and Kritzer, 2010, 2). The World Bank notably supports empirical
work in many new democracies with the goal of increasing their economic prosperity by improving their
legal systems.
4
For well-known examples, see Erickson and Simon (1998); Loh (1984); Monahan and Walker (2010).
5
Holmes (1897, 469). Our emphasis.
6
Justice Stephen G. Breyer of the U.S. Supreme Court (2000, 2) put it this way (our emphasis):
The legal disputes before us increasingly involve the principles and tools of science. Proper resolution of
those disputes matters not just to the litigants, but also to the general public—those who live in our
technologically complex society and whom the law must serve. Our decisions should reflect a proper
scientific and technical understanding so that the law can respond to the needs of the public. … [W]e judges
[are] not asked to become expert statisticians, but we [are] expected to understand how the statistical
analyses worked.
7
To be sure, there are scores of excellent texts aimed at training budding social scientists in research
methods and statistics. On research design/methods, see Babbie (2009); Johnson et al. (2007a); King et al.
(1994). General statistics texts include Agresti and Finlay (2009); DeGroot and Schervish (2012); Freedman