Justice Antonin Scalia passed away Saturday. As German Lopez wrote, "Conservatives praised his incredible ability — as perhaps the court's strongest writer — to eloquently explain their legal positions." Scalia, especially in his majority opinions, unquestionably had a major impact on the development of conservative jurisprudence.

What has received less attention is how much Scalia shaped and improved liberal jurisprudence by being an attentive and critical reader. But shape and improve it he did. Justice Ruth Bader Ginsburg recently wrote, in a tribute to her deceased colleague, that she and Scalia "disagreed now and then, but when I wrote for the Court and received a Scalia dissent, the opinion ultimately released was notably better than my initial circulation."

Are Scalia's contributions to Ginsburg's opinions a result of an accidental and close friendship? Scholarship on judicial interaction suggests the institution of the Supreme Court invites this kind of jurisprudence-improving interaction. This explanation builds, for example, on the intuition of a game-theoretic model by Jeffrey Lax and Charles Cameron (2007): A forceful judge who disagrees with another judge's views incentivizes that second judge to clarify and hone her argument, especially if she is trying to win him over.

The model focuses on two basic characteristics of judicial opinions: 1) their political content (over which we tend to think Justice Scalia and colleagues like Justice Ginsburg disagree), and 2) their quality (internal logical consistency, careful argumentation, and other attributes we think all justices can agree on).

Suppose that a judge is more likely to join an opinion circulated by his colleague the more he likes it, either because he agrees with its politics or because he thinks it is well-argued. If a liberal judge wants to revise her draft opinion in order to persuade a judge like Scalia to join it, she can play one of two tactics: 1) moderate the opinion's political characteristic, i.e., make it more conservative, or 2) maintain the opinion's liberalism but improve its quality. Therefore, Scalia's presence on the Court improves the argumentation in liberal opinions.

Lax and Cameron's models clearly articulate this intuition, but it is much older than that. The architects of the Supreme Court allowed justices to dissent in order to encourage exactly this interaction. When Americans first established federal courts, they had a choice between the traditional French method of opinion writing, where the Court issues one opinion and no justice may write separately, and the traditional English ("seriatim") method, in which each justice must write separately.

Endorsing the seriatim practice, Thomas Jefferson argued that prohibiting dissent shielded "the lazy, the modest and the incompetent" from having to develop their opinions fully (quoted in Jackson 1969, 23). Decades later, Justice William Brennan argued that "vigorous debate improves the final product by forcing the prevailing side to deal with the hardest questions urged by the losing side" (Brennan 1985). And so justices may dissent, and in deciding whether to do so must critique the majority opinion.

Under the right circumstances, conservatives can be important for the development of good liberal law

However, the game-theoretic scholarship on the institutional Supreme Court is not uniformly so optimistic about judicial decision-making. Formally modeling the interaction between justices can find conditions under which this optimistic perspective is not borne out. The story about quality compensating for politics concerns only the written opinion itself. But the Supreme Court doesn't just write opinions. It disposes of disputes — decides who wins and who loses — then writes precedential opinions explaining the decision. If the decision about who wins and who loses is too divisive, the optimistic scenario fails.

A model by Carrubba, Friedman, Martin, and Vanberg (2012) shows that when justices write off a colleague as a lost cause, they don't take their views into account during opinion writing. In this model, each decision for the Court consists of two parts: a judgment to dispose of the dispute between the litigants before the Court, and an opinion to guide future decision-making.

When the merits decision irreparably divides the justices — if, for example, a justice refuses to consider any opinion that results in Obamacare being declared constitutional — that justice won't participate in crafting the majority opinion. So the draft opinion does not benefit from those justices' critiques. Instead, the case's facts divide the Court, and the majority builds doctrine on its own. When justices care much more about the case in front of them than about the precedent they're building, the benefits of divergent predilections diminish.

None of this is to say that Justice Scalia was a liberal on the Court. He was not, as any number of anecdotes will reveal. These conservative contributions are easy to observe because they can be seen in his majority opinions. But under the right circumstances, conservatives can be important for the development of good liberal law. These contributions are much harder to observe, for it is the shadow of Scalia's dissent and his critical evaluation that improved liberal opinions behind the scenes.

Justice Ginsburg has attested to this empirically. My colleagues' scholarship suggests that the rational tactic of a Supreme Court justice committed to liberal doctrine — as many commentators presume Ginsburg is — would be to improve the quality of her draft opinions in order to win the support of a justice like Scalia. That tactic reflects the rules established by the founders of the Court. And perhaps testimony to their apparent wisdom is the most fitting tribute to Scalia of all.

References:

Brennan, William J. 1985. "In Defense of Dissents." Hastings Law Journal 37: 427-438.

Carrubba, Cliff, Barry Friedman, Andrew D. Martin, and Georg Vanberg. 2012. "Who Controls the Content of Supreme Court Opinions?" American Journal of Political Science 56(2): 400-412.

Jackson, Percival E. 1969. Dissent in the Supreme Court: A Chronology. University of Oklahoma Press.

Lax, Jeffrey, and Charles Cameron. 2007. "Bargaining and Opinion Assignment on the US Supreme Court." Journal of Law, Economics and Organization. 23(2): 276-302.

Deborah Beim is an assistant professor of political science at Yale University. She studies American politics in general and judicial politics in particular, with a focus on interactions between the US Supreme Court and the Courts of Appeals.