Empirical Legal Studies

Guest Blogger: Sara Benesh

This week's guest blogger is Sara C. Benesh.  She is an Assistant Professor of Political Science at the University of Wisconsin-Milwaukee.  She received her PhD in 1999 from Michigan State University, held a tenure-track position at the University of New Orleans for two years, and joined the faculty at UWM in 2001. Her research focuses on the relationship between the Supreme Court and the U.S. Courts of Appeals, and she is the author of “The U.S. Court of Appeals and the Law of Confessions: Perspectives on the Hierarchy of Justice” (LFB Scholarly) and co-author of “The Supreme in the American Legal System” (with Jeffrey Segal and Harold Spaeth, Cambridge University Press). She is also Co-PI (with Harold Spaeth) on the National Science Foundation-funded “Justice-Centered Databases,” a revision to the celebrated Spaeth Databases. Professor Benesh teaches courses in civil rights and civil liberties, judicial behavior, and political methodology at both the graduate and undergraduate levels.

Abstracts - The Journal of Politics (May 2006)

The upcoming issue of The Journal of Politics (May 2006) will include several articles in the law and courts field. It will also include a new study by Simon Jackman and Paul Sniderman on the effects of deliberation, which remains a popular topic among both political scientists and law professors. (They conclude that at least in one sense, "deliberation is for naught.") Manuscripts of most of the articles are available on the JOP website. Here are the abstracts:

Eileen Braman, "Reasoning on the Threshold: Testing the Separability of Preferences in Legal Decision-Making."

One hundred fifteen law students were given a mock brief with identical legal arguments on both sides of a standing dispute in litigation involving restrictions on political expression of public employees. The content of the expression at issue (pro-choice vs. pro-life) and the jurisdiction where the case was pending (with vs. without controlling authority on the standing issue) were experimentally manipulated. Participants' policy views on (1) abortion, (2) free speech and (3) Hatch Act restrictions were measured to assess their influence on the standing decision. In line with traditional notions of legal reasoning, participants were able to separate their views on Hatch Act restrictions from the standing decision. Opinions on free speech, however, influenced judgments consistent with attitudinal hypotheses. Also, participants’ opinions on abortion interacted with speech content to influence judgments – but in a manner not wholly consistent with legal or attitudinal accounts of decision-making.

To Tell or Not to Tell

I appreciate Todd Peppers’ and Artemus Ward’s responses to my post. But I didn’t say (or mean) that "the journalists are spoiling it for the academics." Rather, I think that most law clerks make no distinction between journalists and academics when deciding whether and how to respond to requests for information. It’s not a distinction I’ve considered myself until now. And to be honest, I remain unpersuaded that it’s the right distinction to make. The fact that academics are less likely to achieve fame and fortune as a result of their work, for example, than are journalists or muckrakers does not persuade me that law clerks should talk to them more freely. Nor do I believe that it is necessarily true that "both clerks and justices have nothing to fear from us poor, dull, eggheads." Although I have not yet read Artemus’ forthcoming book (other than the introduction, which he very kindly shared with me last fall), the press accounts I have seen (those pesky journalists again!) suggest that it is critical of the role of law clerks and Justices’ dependence on them. It may or may not turn out to be a best-seller, but it also is unlikely to reassure those skittish research subjects that there are no downsides to participating in academic work.

The Trouble with Surveys

It’s interesting to me that, as Todd Peppers says, he “ha[s] worried less about low response rates than responses from law clerks who downplay their job responsibilities while exaggerating their employer’s intellectual abilities and moral virtues.” Certainly that’s a problem for survey research, not just surveys of Supreme Court law clerks, but in general. One challenge of surveys is that many people won’t participate. Another challenge is that people who do participate may not give objective responses.

It’s a problem faced both by academics and by journalists. Books like The Brethren and Closed Chambers were criticized as based on information from law clerks who allegedly exaggerated their roles. Now Todd expresses concern that law clerks may have understated their roles. Both cases lead me to question whether maybe we should be trying to find other ways to gather information than surveying law clerks.

Abstract - The Influence of Oral Arguments

In the new issue of the American Political Science Review (Feb. 2006), Timothy Johnson (University of Minnesota), Paul Wahlbeck (George Washington University), and James Spriggs (U.C. Davis) address "The Influence of Oral Arguments on the U.S. Supreme Court." Here is the abstract:

We posit that Supreme Court oral arguments provide justices with useful information that influences their final votes on the merits. To examine the role of these proceedings, we ask the following questions: (1) what factors influence the quality of arguments presented to the Court; and, more importantly, (2) does the quality of a lawyer's oral argument affect the justices' final votes on the merits? We answer these questions by utilizing a unique data source—evaluations Justice Blackmun made of the quality of oral arguments presented to the justices. Our analysis shows that Justice Blackmun's grading of attorneys is somewhat influenced by conventional indicators of the credibility of attorneys and are not simply the product of Justice Blackmun's ideological leanings. We thus suggest they can plausibly be seen as measuring the quality of oral argument. We further show that the probability of a justice voting for a litigant increases dramatically if that litigant's lawyer presents better oral arguments than the competing counsel. These results therefore indicate that this element of the Court's decisional process affects final votes on the merits, and it has implications for how other elite decision makers evaluate and use information.

Conducting Empirical Legal Scholarship Workshop

From Andrew Martin (Wash U):

Conducting Empirical Legal Scholarship Workshop, May 22-24, 2006.  See here.

The Conducting Empirical Legal Scholarship workshop is for law school faculty interested in learning about empirical research.  The workshop will be co-taught by Lee Epstein (soon-to-be at Northwestern University School of Law) and Andrew Martin (Washington University School of Law).  The workshop is co-sponsored by the two schools, and will be held May 22-24, 2006 at the Northwestern law campus.  The course provides the formal training necessary to design, conduct, and assess empirical studies, and to use statistical software (Stata) to analyze and manage data. Participants need no background or knowledge of statistics to enroll in the workshop.

There will also be an advanced workshop this fall on the Washington University campus for the alumni of this introductory workshop and interested others.  This workshop is still in the planning stages; we will post more information when the details are set.

The Duty of Loyalty and Data Collection

I’d like to follow up on Professor Shapiro’s comments about the duty of loyalty that law clerks feel towards their justices.  She writes: “At its strongest, this ethic of loyalty encompasses a belief that the law clerks should never be complicit in presenting the Court in a negative light,” adding “[t]here is no breach of loyalty, no betrayal, in making the Court and the Justices look good.” The question I would like to pose - what if a justice, or the Court itself, merits the harsh spotlight of public examination and censure?  And what are the unanticipated effects of this duty of loyalty on data collection?

Ben’s Chili Bowl v. White House Chefs: Ben Wins

Following up on Carolyn Shapiro’s excellent post, where she points out that “the journalists are spoiling it for the academics,” I want to continue my very serious argument that there is a major difference between the two, that it is easily recognizable, and that both clerks and justices have nothing to fear from us poor, dull, eggheads. I can understand Carolyn’s point about the Greta Garbo defense for the elect and their bosses who don’t have time or patience for us. However, I urge them make time because they are the practitioners who know far better than we do about how their institution functions and what might be done to improve it.

ICPSR Summer (and Spring) Program

Information is now available about ICPSR's next Summer Program in Quantitative Methods of Social Research. The general application deadline is April 28, 2006. ICPSR is now offering two Spring workshops as well.

An Attempt to Empirically Study Legal Scholarship?

See here.

Conference of Censorship & IRBs

Announcement of a Conference on
CENSORSHIP AND INSTITUTIONAL REVIEW BOARDS

April 6-7, 2006 at Northwestern University School of Law

      This conference will explore the threat to First Amendment
      freedoms and to academic freedom from Institutional Review
      Boards ("IRBs"). IRBs are established by universities,
      under federal regulations, for prior review of research.
      Before a professor or student can do research on human
      subjects, he must submit a research proposal to an IRB for
      its approval. Although IRBs rarely deny permission
      outright, they require modification of about 80 percent of
      submitted proposals. Even when research is "exempt," IRBs
      usually require it to be registered. Indeed, IRBs keep
      records of approved, disapproved, and registered research
      for examination by federal officials.

      Of course, it may seem only reasonable that a researcher
      should get permission before doing research on human
      subjects, but IRBs raise important First Amendment
      questions. In particular, there is reason to fear that in
      establishing a system of getting prior permission, the
      regulations on IRBs create a system of licensing speech and
      the press.

AALS Call for Papers

Stephen Choi (NYU) would like to announce the AALS Section on Securities Regulation Call for Papers... Empirical Papers Welcome!

Confessions of a Reluctant Research Subject

I confess. I received Todd Pepper’s one-page survey. I think I filled it out and sent it back, but I’m not sure (Todd might know). I know I didn’t participate any further in his study, despite my interest in his findings, although I don’t recall if I was one of the people he contacted.

That said, if he had requested an interview I likely would have turned him down. Whether my reluctance to participate is due to my views on law clerks’ confidentiality obligations I can’t say for sure. Although some former clerks apparently disagree, in my view confidentiality clearly extends to the cases that came before the Court while I was a law clerk. That duty doesn’t end when the clerkship ends. Conversely, it seems pretty well accepted that confidentiality doesn’t extend to general procedures of the Court, such as how the cert pool works. The in-between cases are the tougher ones, things like the workings of individual Justices’ chambers, which is what Todd and Stephen Wasby are interested in.

Rather than confidentiality, my guess is that much of the reluctance of clerks to talk about their Justices’ chambers is due to two things, neither of which derives from any formal duty of confidentiality. The first is simply wanting to be left alone. Either because of a sense of personal privacy or simply being too busy, many people don’t respond to surveys. (Actually, Todd’s 40% response rate to his initial survey and Stephen’s 41.3% response rate to his both strike me as quite good.) Is it really surprising that busy people aren’t all that interested in participating in empirical research studies? And I say that as an academic who’s very interested in the results of that empirical research.

The Duty of Loyalty

Thanks to William Ford, Todd Peppers, Artemus Ward, and Stephen Wasby for getting this discussion underway. As a law professor who teaches Professional Responsibility (and as a former law clerk), I may come at the question of law clerks as research subjects from a somewhat different perspective from some of my co-panelists. (In fact, I have to confess that I am one of the law clerks who did not respond to Todd Peppers’ survey.) Perhaps surprisingly, however, I am not a confirmed absolutist on the question of law clerk confidentiality, or more accurately, I’m skeptical of absolutism, and I may say more about that later on. But in this first post, I’d like to say a few words about why, in my view, law clerks, especially Supreme Court law clerks, are such skittish subjects.

As others have already noted, the Code of Conduct for Law Clerks of the Supreme Court of the United States made explicit the law clerk duty of confidentiality (and a similar code exists for the lower federal courts). But more important than the Code of Conduct, I believe, are the culture and norms most law clerks internalize. It is not only an ethic of confidentiality, but also an ethic of loyalty both to the clerk’s own Justice and – significantly – to the institution itself. At its strongest, this ethic of loyalty encompasses a belief that the law clerks should never be complicit in presenting the Court in a negative light. (There are of course limitations on this belief. Former law clerks who are academics, for example, should and do feel free to criticize the Court’s jurisprudence.)

Law Clerks and Confidentiality

It appears that a common theme is emerging in our discussions about studying law clerks, to wit, the law clerk code of conduct.  Ironically, not only does the Code of Conduct for Law Clerks of the Supreme Court of the United States (March 3, 1989) create a duty of confidentiality, but in recent years the Supreme Court has made the code itself confidential.  In writing my book, I contacted the Public Information Office of the Supreme Court and requested a copy of the code.  My request was denied.  I then contacted Chief Justice Rehnquist's chambers, only to receive a short, curt letter from the Chief Justice himself - again denying my request to see a copy of the code.  I later found a copy in the personal papers of Justice Thurgood Marshall at the Library of Congress.

The code of conduct is divided into six ethical canons.  Relevant to this discussion, the code states that law clerks owe both their individual justices and the Court itself "complete confidentiality, accuracy, and loyalty" (emphasis added).  The Code reminds the law clerk that the relationship between the law clerk and the justice is "essentially a confidential one," adding that the law clerk "cannot divulge any confidential information received in the course of the law clerk's duties."  Curiously, the phrase "confidential information" is not defined.  In fact, the code allows the individual justices to create "more stringent" ethical standards than those imposed by the code.  Thus, the justices  can essentially define confidentiality as they see fit -confidentiality could include not only discussions about specific cases, but the kind of soup that was served at a justice's dinner party for the clerks or how many fouls Justice Byron White committed during a game of basketball on the "highest court in the land."

Why such secrecy about a code of conduct for government employees?  At the time, I wondered if denying researchers copies of the code of conduct, and thus preventing researchers from understanding the specific ethical duties placed on law clerks, resulted in researchers being unable to make a convincing case to former law clerks that their research agenda did not run afoul of the code of conduct.   How can a researcher argue that her questionnaire does not violate the duty of confidentiality if the researcher does not know the scope of that duty? Whatever the reason, making the rules about confidentiality confidential places additional and unnecessary roadblocks in the path of the researcher.

Hollywood Back Lot Meets Ivory Tower

Following the thoughtful posts of my colleagues Steve Wasby and Todd Peppers, I thought I would discuss why it is important that law clerks speak to us about their experiences and why they should not be afraid of violating “confidentiality.” Because we are having this discussion on the Empirical Legal Studies blog, I think notice should be taken of the difference between journalistic accounts of clerks and courts such as Bob Woodward and Scott Armstrong’s The Brethren and empirical law and courts research such as Peppers’ Courtiers of the Marble Palace and why it is important for clerks to make an effort to work with those of us in the scholarly community.

A little over a year ago, I got a phone call from a film company in Hollywood. The first question the Hollywood executive asked me was, “Who is your agent?” Of course I don’t have an agent, nor have I ever received a call from a movie studio. I soon found out that the company was in the process of developing a big-budget Hollywood blockbuster on Supreme Court law clerks. They found out that I was writing on clerks and wanted to get together to discuss their project. I am from Los Angeles and was going to be home for the Holidays visiting my family anyway, so I thought it would be fun to “take a meeting” on the Universal Studios back lot to see the Hollywood game up close. With my all-access pass to the place I had only previously visited via a tram-ride past a mechanical shark, the house from “Psycho,” and the town square from “Back to the Future,” I drove my car past the bungalows occupied by Steven Spielberg’s Amblin Entertainment, pulled into my guest parking space next to the one marked, “Reserved: Jill Hennessey” and proceeded to the bungalow of the film company that was going to make the big law clerk blockbuster to end all blockbusters.

WSJ on Law Clerks

See here.

Wash. Post: "The Varying Influence of Clerks"

The article, about the influence of law clerks, is available here.

Clerks as Subjects

Most attention to clerks has been to those in the United States Supreme Court, and with the addition this fall of two important books on that subject, by Todd Peppers, and by Artemus Ward and David Weiden, respectively, we’ll know even more about them. Less attention has been given to clerks in either the lower federal courts (but see Jonathan Matthew Cohen’s Inside Appellate Courts) or in the state supreme courts (but see articles by the late Charles Sheldon). Relevant to studying clerks -- and I assume a “yes” answer to the question, “Are they valid objects of research?” -- is the question of whether there are problems connected with law clerks as research subjects.

The following draws on my experience in conducting a study, part of a larger project, of the clerks of a long-serving judge, now a senior federal appellate judge but who had previously served as a state supreme court justice and as a U.S. district judge. The research on clerks entailed interviews with some of the judge’s former clerks and a mail survey of the others, supplemented with informal observation when I was in the judges’ chambers; having luncheons with the clerks and the judge; and observing a session in which the judge and a set of clerks prepared for an argument calendar. The latter elements, while sporadic and not systematic, assisted in understanding “what clerks do,” my primary research interest. (I was also interested in why the clerks wanted to clerk, why they wished to clerk in the judge’s court and for that judge; how they evaluated their experience as a clerk; and what if any post-clerkship contacts they had with the judge.)

Studying the Elusive Law Clerk

My research focuses on what I call the “clerkship institution,” namely, the rules and norms that surround the hiring and utilization of Supreme Court law clerks. Specifically, I draw upon principal-agent theory to generate and test hypotheses as to the evolution of the clerkship institution over the last 120 years. While I’m interested in the question of law clerk influence, I submit that the influence debate cannot be resolved until we first have a comprehensive picture of the rules and norms that surround and confine the law clerk as well as an appreciation of how these rules and norms have evolved.

If I were to summarize in one word what United States Supreme Court law clerks are like as research subjects, it would be “challenging.” Books like The Brethren and Closed Chambers have not helped pull the reluctant law clerk out of the shadows of the Marble Palace.

Blog Forum - Law Clerks as Research Subjects

This week, the ELS Blog presents its first Blog Forum, the topic of which is law clerks as research subjects. This topic is particularly timely. Two major studies of law clerks are scheduled for release this April, Todd Peppers’ Courtiers of the Marble Palace: The Rise and Influence of the Supreme Court Law Clerk (Stanford) and Artemus Ward’s and David L. Weiden’s Sorcerers’ Apprentices (NYU). 

As Todd Peppers notes in his post, law clerks can be “tricky” research subjects. Based on my experience on a survey project with Jason Czarnezki, there are two major issues in working with former clerks. The first is that many of them now work at law firms and are extraordinarily busy. I am not sure that much can be done to deal with this issue. You can send multiple requests (which we did do). You can call (which we did not do). But nothing can make your survey billable.

A Hybrid Empirical Legal Studies Law Journal?

There has been much discussion here and here about whether empirical scholars in law should publish in peer-reviewed journals or general subject student-edited law reviews.  These conversations have not mentioned the existence of topic-specific law reviews (e.g., Stanford Environmental Law Journal, Administrative Law Review, Harvard Civil Rights-Civil Liberties Law Review). Might there be an available niche for a topic-specific law review focusing on empirical legal studies? Student editors of such a journal might be more likely to be J.D./Ph.D. candidates, and any law school journal could develop an article review process that involves faculty and blind outside review. In other words, in the future, might there be a hybrid topic-specific law review focusing on empirical legal studies where J.D./Ph.D. law students make the initial cut and edits/cite-checking of articles, with final selection of articles done by qualified faculty and high-level student editors?  Stated another way, is there a journal model that could take full advantage of both student and faculty efforts?

Call for Papers: Conference on Empirical Legal Studies

Click here for the Announcement and Call for Papers for the First Annual Conference of Empirical Legal Studies at the University of Texas Law School on October 27-28, 2006 (Paper Submission Deadline = June 30, 2006).

Course Syllabi

The Society for Political Methodology maintains a collection of course syllabi by top methodologists in the areas of "Introductory Statistical Methods, Advanced Statistical Methods, Scope and Methods, and Qualitative Methods at both the undergraduate and graduate levels."

Law & Psychology Conference

As most law and psych folk probably know, this year's annual conference of the American Psychology/Law Society (APLS) is in sunny St. Petersburg, FL.  For those less familiar, Jeremy Blumenthal (Syracuse) notes on PrawfsBlawg that the APLS "does a great deal of empirical law-related work, publishes Law and Human Behavior, one of the more heavily cited non-law-review publications, and holds very cool conferences in fun places."  Jeremy also remarks that the "APLS is a great source not only for law profs to learn about empirical research going on in psychology and related fields, but also to collaborate with empirical social scientists – but even more important, I think, to broaden the scope of the sort of experimental research that goes on."

Supreme Court Ideology Project

Check out the Supreme Court Ideology Project: "This website uses Bayesian ideal point estimation to update our beliefs about the location of Supreme Court justices. We begin with a prior belief about the location of each justice and update these beliefs after each opinion delivered by the court, learning from the justices' votes what their underlying ideologies are likely to be."   "The figure below shows the posterior densities for our beliefs about each of the justices' ideal points, updated through the most recent vote cast.  "

Are Law Schools Hiring More PhDs?

Once again Larry Solum is compiling data for his Entry Level Hiring Report in Law Schools.  In last year's report, 30 of 173 candidates (17.3%) had PhDs or DPhils.  My guess is that this percentage will increase over time.   This hypothesis is based on: the increased number of legal scholars now doing empirical work; that law schools are hiring non-JD professors who have PhDs in other fields; the increase in the number of JD/PhD programs available to students; and that law schools are developing their own PhD programs (e.g., Vanderbilt Law's PhD in Law & Economics). 

Is my guess correct?  Will more future law professors be JD/PhDs?  Might law schools soon subsidize PhDs for its faculty?  Are law school hiring committees interviewing more candidates with PhDs?  Are committees actively looking for candidates with PhDs?  Comments are open.

The Polls - Constitutional Awareness

Since it shows more public knowledge about The Simpsons and American Idol than the Constitution (but with no mention of the Three Stooges), a new study released yesterday by the McCormick Tribune Freedom Museum is getting a fair amount of coverage. If you want to see the source material rather than newspaper summaries, go here for the press release or here for the full report. The Chicago Tribune got it right: "A survey released Wednesday showcases a bit of data that should surprise nobody[.]"

One highlight from the survey: About 21% of respondents thought the First Amendment guarantees the right to own and raise pets. I am always interested in finding examples of exotic constitutional claims—i.e., "rights talk" data points—and I have see this one in action before. Specifically, it was a constitutional right to own 400-pound Bengal-Siberian tigers (and maybe cougars as well): "I think it's my right as a U.S. citizen to have these cats.... If people say we can't have them, they're messing with my constitutional rights." Alex Tresniowski and Gabrielle Cosgriff, Cat Fanciers: With an Increasing Number of Texans Keeping Tigers as Pets, Some in the State Fear More Maulings and Deaths, People, April 16, 2001, at 111.

Has Empirical Legal Scholarship Resolved Theoretical Debates?

The relevance of empirical work is determined largely by its ability to resolve questions in theoretical debates, and hopefully move those debates forward.  I'm encouraging comments from others on areas that they believe have been largely resolved, or where empirical work has helped move the theoretical debate forward.  (Or maybe where we've been spinning our wheels?)

To get things started, one area of particular interest to me has been the rapidly growing body of work on the effect of exceptions to employment at will.  Through the 1970s and 80s, many states recognized exceptions to the employment at will rule.  Some scholars (notably Stewart Schwab) suggested that this trend may have been motivated by the desire of courts to police long-term employment contracts for opportunism.  Others (notably Richard Epstein) worried that these exceptions would simply increase firing costs. In this case, present employees are benefited by the rule that makes it harder to dismiss them, but future workers face costs as employers are now more wary of hiring anyone.

Miles (2000), Schanzenbach (2003); Autor (2003); Kugler & St. Paul (2004); and Autor, Donohue & Schwab (2006), all found remarkably consistent results: exceptions to employment at will appear to have raised firing costs, and employers responded by turning to temporary help, retaining current employees longer, and (perhaps) employing fewer workers period.  These authors used different data sets, different  outcome variables, different methodologies, and different dating techniques for deterring the recognition of exceptions.  Given this, the outcomes are remarkably consistent. 

A new paper by McLeod & Nakavachara (available here) refines the previous analysis a bit by suggesting that workers for whom joint investments are important may have benefited from employment-at-will exceptions (specifically the "good faith exception").  Unfortunately, lower-skilled workers were adversely affected.  The authors say the results are preliminary, but the work seems to be taking the next logical step in the literature. 

This may revive Schwab's theory, but raises a difficult public policy question.  If the results are correct, the rule works out to a wealth transfer that is probably pretty regressive (and given the previous work mentioned above, probably a net negative)--unless the courts could refine the rule to only protect certain classes of employees, which is likely beyond the ability of the common law.

So here we have an example of consistent work, informed by theory, and now moving theory forward--with some implications for public policy.

Are there areas where we have been spinning our wheels?  One candidate that comes to my mind is empirical work on tort reform.  It's not my area, but my impression is that people find no effects, some effect, opposite effects, and so forth.   

Comments welcome. 

[Exact citations for the articles referenced here are available in the linked paper.]

Brundney & Ditslear on Legislative History

James Brundney & Corey Ditslear have written The Decline and Fall of Legislative History (Judicature, Vol. 89, No. 4).  Looking at the Burger and Rehnquist Eras, they have found a decline in reliance on legislative history. 

New Book - The Politics of Precedent

I received a desk copy of Thomas Hansford's and James Spriggs' new book, The Politics of Precedent on the U.S. Supreme Court (Princeton 2006), which Amazon reports as being available this Friday, March 3rd. Their "key" question is: "Why and when does the Court interpret its precedent positively or negatively." (p. 8) In answering this question, Hansford and Spriggs expressly recognize the role of both policy and legal concerns in judicial decision-making—even in the court where, relative to other American courts, ideology likely matters most. 

Proxies or Instruments for Lawsuit “Quality”

How plausible is it that models seeking to explain variation in bivariate litigation outcomes (e.g., success/failure) among lawsuits brought by various (and standard) party types (e.g., individuals, corporations, insurance companies, government) might need to account for the quality (or strength) of legal claims pushed or arguments advanced? Put slightly differently, is there any reason to assume, ex ante, that lawsuit quality will systematically vary across party types? (My query assumes that a lawsuit’s quality informs the probability of its success.) If so, and to the extent that endogeneity might lurk as a methodological issue, what are prudent responses?

At one level, data selection can perform some crude filtering tasks, at least at the margins. For example, by limiting a dataset to only cases fully litigated and generating a written, published opinion researchers functionally screen lawsuits that do not survive the preliminary motion stage. (This implies, rightly or wrongly, that lawsuits kicked at the preliminary motion stage possess less legal “quality” than those lawsuits that survive preliminary motions.  Limiting a dataset to written, published opinions, however, swaps one source of potential bias for another.) If one aspires a more finely grained proxy for lawsuit quality, however, do other variables make sense?--keeping in mind that any such variable must be objective, reliable, replicable, etc. On a related though distinct matter, suggestions about how researchers might instrument for party types in this context are also welcome.