Democrats and liberals have a nightmare vision of the Supreme Court's future: President Obama is defeated for re-election next year, and Justice Ruth Bader Ginsburg, at 78 the oldest justice, soon finds her health will not allow her to continue on the bench.
The new Republican president appoints Justice Ginsburg's successor, cementing conservative domination of the court, and soon the justices roll back decisions in favor of abortion rights and affirmative action.
But Justice Ginsburg could retire now, and allow Mr. Obama to name a like-minded liberal successor whose confirmation would be in the hands of a Democrat-controlled Senate. "She has in her power the ability to prevent a real shift in the balance of power on the court," said Erwin Chemerinsky, dean of the University of California at Irvine law school. "On the other hand, there's the personal. How do you decide to leave the United States Supreme Court?"
For now, Justice Ginsburg's answer is, you don't.
There are few more indelicate questions to put to a Supreme Court justice, but Justice Ginsburg has said gracefully, and with apparent good humor, that the president should not expect a retirement letter before 2015.
She will turn 82 that year, the same age Justice Louis Brandeis was when he left the court in 1939. Justice Ginsburg, who is Jewish, has said she wants to emulate the court's first Jewish justice. Justices Stephen G. Breyer and Elena Kagan are also Jewish.
While declining an interview on the topic, Justice Ginsburg pointed in a note to the Associated Press to another marker she has laid down, that she is awaiting the end of a traveling art exhibition that includes a painting that usually hangs in her office by the German emigre Josef Albers.
"Couldn't think of leaving until after it is returned to me, which won't be anytime soon," she wrote.
Certainly there is no indication that Justice Ginsburg is slowing down on the job, even after she underwent surgery two years ago for pancreatic cancer that her doctors said was detected at a very early stage.
Appointed by President Clinton in 1993, she served for the first time this term with two other women, Justices Kagan and Sonia Sotomayor, and as the senior liberal justice, a role that gives her the power to assign dissenting opinions when she is on the losing side of ideologically split rulings.
On a personal level, she appeared to take comfort in her work as she adjusted to life without her husband, Martin, who died a year ago.
And she doesn't have to look very far ahead to imagine having a vote in some of the most important cases of her time on the court, including the challenge to Mr. Obama's health care overhaul and the fight over gay marriage.
Laura Krugman Ray, a Widener University law professor who has written about Justice Ginsburg, said it is easy to think she would want to have a voice in those cases.
"I think the court is enormously important for her," Ms. Ray said. "And especially now after husband's death, you wonder what she can see herself doing if she were not on the court."
Justice Ginsburg, the second woman on the bench, has only to look at the first for a cautionary tale about retiring. Justice Sandra Day O'Connor announced her retirement in 2005 in part so she could take care of her ailing husband, John. Two months later, Chief Justice William Rehnquist died in office.
Meanwhile, John O'Connor's health declined much faster than his wife anticipated, and he soon was living in a nursing home in Arizona. Would she have quit the court had she known what awaited?
In retirement, Justice O'Connor has maintained a busy schedule, hearing cases on federal appeals courts as well as advocating for Alzheimer's funding, improved civics education and merit selection, rather than partisan election, of state judges.
Justice O'Connor, now 81, also has said she that she regrets that some of her decisions have been "dismantled" by the Supreme Court. Justice Samuel A. Alito Jr., who took her seat in 2006, has voted differently from Justice O'Connor in key cases involving abortion rights, campaign finance and the use of race in governmental policies.
But some on the left say that the focus on the personal is misplaced. Justice Ginsburg needs to put self-interest aside and act for the good of the issues they believe in, Harvard law professor Randall Kennedy wrote recently. Mr. Kennedy said 72-year-old Justice Breyer should leave, too.
Too much is at stake, and both life and politics are too fickle to take the risk that everything will work out as the justices desire, Mr. Kennedy said.
David Garrow, a Cambridge University historian who follows the court, said Justice Ginsburg's situation points to an institutional problem for the court, "the arguably narcissistic attitude that longer is better."
The longest-serving justice, William Douglas, was on the court for more than 36 1/2 years, reluctant to retire even after a debilitating stroke. "History teaches us that often longer is not better," Mr. Garrow said.