Presidential Election Could Reshape an Aging Supreme Court WASHINGTON - Justice Ruth Bader Ginsburg is not known for delivering laugh lines. But she drew chuckles from a group of liberal lawyers not long ago while recalling how Justice Elena Kagan, 52, had suggested during an oral argument before the Supreme Court that people born before 1948 were old. "Next year I will turn 80, God willing," Justice Ginsburg said. " "I'm not all that old," I told my youngest colleague." Justice Ginsburg is the senior member of a court that includes four justices in their 70s, making it among the oldest courts since the New Deal era. Its decisions during this historic "flood season," as Justice Ginsburg described the end-of-term rush, are likely to make the panel - and the tenure of some of the justices - a significant issue in the presidential campaign. On Monday, the court's ruling in an Arizona immigration case delivered a partial victory to the Obama administration but also deeply disappointed some Latinos by upholding a requirement that police officers check the immigration status of anyone they stop if they suspect that the person is in the country illegally. On Thursday, the court is expected to announce its decision on President Obama's health care law, one of the most consequential cases in decades. This fall, the court will take on an affirmative action case that could end preferential treatment at public universities, and it might hear a case involving same-sex marriage. The winner of the race for president will inherit a group of justices who frequently split 5 to 4 along ideological lines. That suggests that the next president could have a powerful impact if he gets to replace a justice of the opposing side. "This election could shape the court for decades to come," said Nan Aron, president of the Alliance for Justice, a liberal advocacy group. It is, of course, impossible to predict when a vacancy will occur. Justice John Paul Stevens spent 35 years on the court and retired at 90, while Justice Robert H. Jackson, who served in the 1950s, died of a heart attack at 62. A 2006 study in the Harvard Journal of Law and Public Policy found that the average retirement age for justices was 78.7. Justice Ginsburg, a stalwart of the court's liberal bloc, has been treated for pancreatic cancer. Justice Antonin Scalia, the court's most visible conservative, is 76. Justice Anthony M. Kennedy, frequently the swing vote, is 75. And Justice Stephen G. Breyer, like Justice Ginsburg a Democratic appointee, is about to turn 74. None have shown any interest in stepping down, though Randall L. Kennedy, a liberal Harvard Law professor, argued last year that Justices Ginsburg and Breyer should quit so Mr. Obama could name younger like-minded replacements. Professor Kennedy presented his argument in an article published in The New Republic under the headline "The Case for Early Retirement." "Both are unlikely to be able to outlast a two-term Republican presidential administration," Professor Kennedy wrote, adding, "What's more, both are, well, old." It was a provocative article; in an interview, Professor Kennedy said the suggestion that a justice should retire for purely political reasons was "viewed as somewhat unseemly" by many of his colleagues. And those close to Justice Ginsburg say that while she may appear frail, she is in fact in good health. "Justices have a conflicting set of obligations," said Geoffrey R. Stone, a constitutional law professor at the University of Chicago, where Mr. Obama once taught. On the one hand, they have an obligation to serve their terms as long as they feel it's in the interest of the nation, and as long as they feel they can do the job well. But they have a conflicting desire, which is to perpetuate their view on the court. It's a political and personal judgment which they have to make for themselves. Justices leave for a variety of reasons. Sandra Day O'Connor, for instance, left the court at 75 to take care of her husband. Professor Kennedy insists it was "not accidental" that, having been appointed by Ronald Reagan, a Republican, she resigned while George W. Bush was president. Her announcement in July 2005 caught official Washington by surprise; many had expected the chief justice, William H. Rehnquist, who was being treated for thyroid cancer, to step down. But Justice Rehnquist privately told Justice O'Connor that he had no intention of quitting. Two months later, he was dead, and Justice O'Connor, to avoid leaving a second vacancy, agreed to stay on the court until her replacement was confirmed. The court's most recent retirees, Justice David H. Souter and Justice Stevens, were appointed by Republicans, but as the court shifted right, they moved left. Justice Souter, who retired at 69, made it clear that he disliked Washington and wanted to move back home to New Hampshire. Both he and Justice Stevens, by then the leader of the court's liberal wing, stayed on until Mr. Obama became president. "One can infer that they were waiting," Professor Stone said. Others have also waited until a president of their liking occupied the White House. Byron R. White, appointed by John F. Kennedy, retired early in Bill Clinton's presidency. Potter Stewart, appointed by Dwight D. Eisenhower, left during Mr. Reagan's first term. Harry A. Blackmun, a Nixon appointee best known for writing the opinion in Roe v. Wade, retired at 85, under Mr. Clinton. "He had migrated so far to the left that he didn't want a Republican to replace him," said Linda Greenhouse, the author of a Blackmun biography and a former reporter for The New York Times. He achieved his goal. But waiting has its drawbacks. Justice Thurgood Marshall, the civil rights icon, waited through the Reagan and Bush years for a Democratic president, but his health did not hold out. On the day after he announced his retirement, he had a news conference. "I'm old," Justice Marshall, then 82, told reporters. I'm getting old and falling apart. He was replaced by Justice Clarence Thomas, whose views were antithetical to his own. "One of the tragedies of his career," said Professor Kennedy, who served as a clerk for Justice Marshall, "was that he didn't think this through enough." Some say that Justice Ginsburg could face the same situation, now that Mr. Obama is caught in a tough re-election campaign against Mitt Romney. "She is betting everything she believes on either Obama winning re-election or her being able to survive until 2017," said Lucas A. Powe Jr., a Supreme Court historian at the University of Texas School of Law. If she dies and Romney wins, the Supreme Court will be the most conservative in history.