With Kagan's Confirmation, Supreme Court Is Divided by Party; Can Algorithm Predict Votes?
For the first time in a century, the ideological positions of U.S. Supreme Court justices are all linked to the parties of the presidents who appointed them.
The change took place last year when Justice Elena Kagan was confirmed to replace Justice John Paul Stevens, a liberal appointed by Republican president Gerald Ford, according to a Slate article. Now Democratic appointees tend to favor liberal positions, while the Republicans tend to be more conservative.
In 12 out of 18 cases decided last year by 5-4 or 5-3 votes, the court’s Democratic appointees were on one side, and the Republican appointees on the other. Justice Anthony M. Kennedy, the swing justice, still agreed with the conservatives more often than the liberals.
Slate offers some reasons for the polarization. First, political parties themselves used to be more divided between liberal and conservative factions. And past presidents didn’t always make appointments based on ideology. They also considered the appeal to voters, the rewards for allies, and the benefits of avoiding confirmation battles.
Meanwhile, Spanish researchers have developed a mathematical model to predict justices’ votes based on those of other justices in the same case. In 5-4 cases, their algorithm correctly predicted votes 77 percent of the time, according to the study. The International Business Times reports on the conclusions. (Hat tip to Slashdot.)
“The authors of the report, researchers Roger Guimera and Marta Sales-Pardo of Spain, set out to ask whether one of the nine Supreme Court justices could be plucked from the bench and replaced with an algorithm that does not take into account the law or the case at issue, but does take into account the other justices’ votes and the court’s record,” the IBT story says. “These researchers say their computational models, using methods developed to analyze complex social networks, are just as accurate in predicting a justice’s decision as forecasts from legal experts.”
The researchers studied the first 150 cases of court beginning with the Warren court in 1953 through the last Rehnquist court in 2004.
