Kagan’s arrival could create an unprecedented party-based alignment, with five Republican appointees often outvoting their four Democratic colleagues. She would succeed the retired Justice John Paul Stevens, a Republican appointee who defied party labels by aligning with the court’s liberals on abortion, the death penalty, terrorism, campaign finance and gun rights.
A partisan divide would punctuate a decades-long trend fueled by the increasingly contentious appointment and confirmation process. It would be a new dynamic for a court that has traditionally sought to keep its distance from the partisanship that pervades the other two branches of government.
“To an astonishing extent, a Republican appointment versus a Democratic appointment is going to explain a lot about their votes,” said Christopher L. Eisgruber, the provost of Princeton University in New Jersey and the author of a book on the Supreme Court appointment process. “And that’s worrisome when the court becomes an extension of partisan politics.”
Confirmation of Kagan, President Barack Obama’s second high court nominee, would put four Democratic appointees on the court for the first time since 1971. It would come a year after Obama nominee Sonia Sotomayor succeeded David Souter, another Republican selection who often voted with his Democratic colleagues.
Kagan would join a court that divided almost along party lines this year in 5-4 rulings that struck down limits on corporate campaign spending -- prompting criticism from Obama in his State of the Union address -- and required states and cities to respect gun rights.
In each case, the majority consisted of five Republican appointees -- Chief Justice John Roberts and Justices Antonin Scalia, Clarence Thomas, Samuel Alito and Anthony Kennedy --with Stevens and Democratic appointees Sotomayor, Stephen Breyer and Ruth Bader Ginsburg in the minority. Barring illness, that five- vote majority is likely to hold sway for some time given that no Republican has voiced interest in retiring.
Until now, the court has always had justices who crossed party lines. When the court struck down parts of Democratic President Franklin Roosevelt’s New Deal in the 1930s, it did so over objections from Republican appointees Benjamin Cardozo and Harlan Fiske Stone.
Supporting Civil Rights
And when the court buttressed civil rights and limited police power starting in the 1950s, Republican appointees including Chief Justice Earl Warren and Justice William Brennan were in the vanguard -- at times over the dissent of Democratic appointee Byron White.
“Presidents have always paid attention to ideology,” Eisgruber said. The difference now is that “they’re paying more attention to it and they’re getting better at predicting what their nominees will do.”
Sotomayor so far is a prime example. The newest justice agreed with fellow Democratic appointees Breyer and Ginsburg in about 80 percent of the non-unanimous cases during her first term, according to the Scotusblog website, which tracks the court. By comparison, Sotomayor agreed with Scalia, Thomas and Alito in about 40 percent of those cases.
Kagan’s career suggests she will join the Democratic group more often than not. She served for four years in President Bill Clinton’s White House, working to support abortion rights, bolster weapons restrictions and authorize federal regulation of tobacco.
“My views are generally progressive,” the lifelong Democrat said at her confirmation hearing in June.
Unity among Republican appointees can be more elusive, largely because of Kennedy, who has joined the liberals in backing some restrictions on the death penalty and in bolstering the rights of wartime detainees.
Perhaps more so than any other justice, the 74-year-old Kennedy will determine the depth of the partisan divide. Kennedy may be decisive should the court take up cases involving gay marriage and Obama’s health-care overhaul.
The partisan divide is a product of the ideological uniformity that has developed within the two parties, said Mark Tushnet, a constitutional law professor at Harvard Law School. Conservative Southern Democrats and liberal-to-moderate Republicans no longer are enough of a force in their respective parties to secure a Supreme Court nomination, he said.
“The phenomenon reflects what’s happening in the parties,” Tushnet said. “And probably the best evidence of that is the emergence, seemingly permanent, of sharp partisan divisions in the Senate’s confirmation votes.”
Indeed, Sotomayor received only nine Republican votes and Alito got just four Democratic votes, and so far no Republican has announced support for Kagan. Roberts received 22 Democratic votes in 2005.
Of course, justices always have the potential to surprise, and Kagan is no exception. The 50-year-old may serve for decades, giving her plenty of time to diverge from Obama and from her fellow Democratic appointees on at least some issues.
“Sotomayor and, if confirmed, Kagan, have not weighed in on many of these questions,” said Adam Winkler, a constitutional law professor at the University of California at Los Angeles. “We may assume they will vote a particular way, but that’s just an assumption.”