Want to know how the Supreme Court will rule on a hot-button case like gay marriage? Just follow the oral arguments and see who interrupts the lawyers. That's the conclusion of a study from the University of Arkansas, which found that Supreme Court Justices are more likely to interrupt and counter a counsel's arguments when they do not agree with them.
The authors studied 11 cases from 2009 and 2010, along with the voting records of eight of the justices on those cases and how often those justices interrupted. Justice Clarence Thomas's votes were not studied, as he has not spoken during a court argument in the last five years.
"Justices get to interrupt and they do it often. We saw that there were around 140 interruptions per case, and we thought that had to mean something," says Christopher Kimmel, an honors undergraduate at the university and the lead author of the study.
And it did. In cases they studied that were more politically charged, such as the 2010 Citizens United v. FEC case that allowed for unrestricted political spending by corporations and unions, "Justices come to the bench knowing exactly what they believe about the issue," says Kimmel, "and then they interrupt to get a justice who is on the fence to swing" their vote.
That case saw 178 interruptions—much higher than the 140 interruption per case average.
While research has been done on interruptions in the Supreme Court before, interruptions by individual justices has never been the subject of published research.. And some of the findings about the justices upend expectations.
Justice Antonin Scalia, for example, considered an ideological conservative, was the most active justice in interruptions—yet he consistently interrupted arguments from both sides, only barely favoring those with whom he agreed.
Interruptions by Chief Justice John Roberts, however, were not so evenly split. "On every single case, he exhibited the hypothesized behavior indicating that his interruptions, as well as his statements and questioning, were highly predictive of his intended vote," the study writes. That is, he interrupted those with whom he disagreed far more often than those with whom he agreed.
"He goes after the other side, and it is a strategy," says Patrick Stewart, the second author on the study and an associate professor of political science at the University of Arkansas. "It might be a more conscious [effort] with him because he's studied it and written on it."
Stewart is referring to a paper Roberts published in 2005, in which the Chief Justice wrote that Supreme Court oral argument has "always been vigorous and rigorous" but that today in even well-argued cases "sometimes the judges get in the way."
Though the University of Arkansas study looks at how justices get in the way, it does not examine why they do it.
But an earlier University of Arkansas study, in 1992, suggests the interruptions may be a conscious effort. Justices interrupt to "gain dominance, and at the same time reduce the status and power of a target," the study found.
If the court takes up the issue of gay marriage, which they could decide to do on Monday, Kimmel says to expect a lot of interruptions.
"You're going to get a lot of interruptions, and a lot of telling interruptions," he says, "that will show pretty well where the justices will come down."
Elizabeth Flock is a staff writer for U.S. News & World Report. You can follow her on Twitter or Facebook or reach her at email@example.com.