Ezra Klein:

Either way, it seems unlikely today’s oral arguments will dislodge the justice’s conclusions. Indeed, it would seem faintly ridiculous, and possibly even irresponsible, for the justices to permit one lawyer having a particularly bad or good day before the bench to flip such a consequential case. But what do the experts think?

Here is what at least some experts think:

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.

That is from a 2006 paper by Timothy Johnson, my GW colleague Paul Wahlbeck, and James Spriggs.  (See also Johnson’s book).  They examine a random sample of the Court’s cases from 1970-94 (539 in all).

I linked to this article in a 2009 post, and I’ll repeat what I said then:

To be sure, a lawyer’s oral argument is more powerful among justice who are ideologically closer to the lawyer’s position. But even justices on the opposite side can be influenced by a “good” argument.

Of course, these results are average effects across a set of cases, and do not necessarily imply that oral arguments are effective in every case, such as the one before the Court this week.

That said, this research deserves a place in the conversation.

[Cross-posted at The Monkey Cage]

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John Sides is an associate professor of political science at George Washington University.