One candidate taught constitutional law and tapped a former Senate Judiciary Committee chairman as his running mate. The other once helped ease tensions in the Senate over judicial nominations, and has teamed up with a woman whose passionate opposition to abortion has energized conservative Republicans.
The differing experiences between the candidates are an intriguing backdrop to questions about how they would handle lifetime appointments to the Supreme Court, which is split on social policy issues ranging from reproductive rights to the scope of executive power.
On the Democratic side, presidential nominee Barack Obama is a lawyer and former University of Chicago law professor. His running mate, Joe Biden, also a lawyer, led the Senate Judiciary Committee — which vets high court nominees — for eight years.
The Republican side pairs presidential nominee John McCain — a senator who three years ago took the lead in resolving a dispute over President Bush's nominations to federal courts — with Alaska Gov. Sarah Palin. She is a vocal critic of abortion rights whose selection was embraced by conservative Republicans who have made moving the Supreme Court to the right a priority.
During a fall campaign dominated by the economic crisis, debate over two wars and arguments over who is more fit for office, discussion of how the next president will handle Supreme Court nominations largely has been overshadowed. Even so, the differing experiences of Obama, McCain and their running mates offer clues as to how the candidates might approach vacancies on the bench.
The appointment of life-tenured judges can be an administration's most consequential legacy, as Obama and McCain observed in last week's debate. Five of the nine Supreme Court justices are age 70 or older, so a new president might have to make multiple appointments.
Because the court is tightly split over issues such as abortion rights, race-based policies and the handling of Guantanamo Bay detainees, even a change of one justice could alter the law across the nation for decades to come.
Republican presidents have tended in recent decades to appoint men in their 40s and 50s, including Justice Clarence Thomas, who was 43 at the time of his appointment, Chief Justice John Roberts, who was 50, and Justice Samuel Alito, who was 55.
"People don't realize how much is at stake," says Walter Dellinger, who as U.S. solicitor general under President Clinton was the government's top lawyer before the court from 1996-97.
"It is highly likely there will be (up to) three vacancies in the next president's first term," says Theodore Olson, U.S. solicitor general from 2001-04. "Justices serve on average 25 years. That's six presidential terms. They make life or death decisions."
Olson, a chairman of McCain's legal team, successfully argued Bush v. Gore, in which the conservative-led Supreme Court resolved the 2000 Florida election dispute and gave Republican George W. Bush the White House.
Just whom either candidate would choose for the high court is impossible to know. Based on their backgrounds and outlooks, Obama and Biden likely would be centrally involved in the selection process. Obama says he wants a justice who will "stand up" for the disadvantaged.
McCain and Palin likely would hew to the values of their conservative base and seek nominees who would narrowly interpret the law, rather than expansively construe it to solve problems of the underdog. McCain has said he does not want judges who will reach out to solve social problems that might be best left to elected officials.
The eldest justices on the current court, John Paul Stevens, 88, and Ruth Bader Ginsburg, 75, are among the most liberal. If they retire and are succeeded by conservatives, the court would tip considerably. The appointment of Alito, who replaced retired justice Sandra Day O'Connor in 2006, has altered the law on abortion, race and campaign finance because he has voted more conservatively than O'Connor.
"It is not at all implausible that we are nominating someone for the next 50 years," says Northwestern University law professor John McGinnis.
As emerging technology introduces new legal questions, and gay marriage and other contemporary issues reach the courts, the next decades will bring a wide and unpredictable swath of cases. The court also is likely to see continued challenges to Roe v. Wade, the 1973 decision that made abortion legal nationwide.
"Roe v. Wade is at the top of the list" of what could be immediately at stake in court appointments, Cornell University law professor Michael Dorf says. He emphasizes that the bench would change more dramatically if a McCain pick succeeded a liberal. Five justices — a bare majority that includes the four liberals — have endorsed the 1973 landmark ruling on abortion.
"Roe v. Wade probably hangs in the balance" this election, Obama, an abortion-rights supporter, said during the presidential debate last week. McCain has termed Roe "a bad decision" and says it should be reversed, but he said during the debate he would not use opposition to the ruling as a "litmus test" for his potential court nominees.
The Senate has the power to confirm or reject nominees. Democrats currently control the Senate, and the difficult economic climate, along with Republican Bush's unpopularity, makes it likely they will see substantial gains in November.
If Democrats make significant headway in the Senate and McCain wins the presidency, he likely would be blocked from choosing an ultraconservative jurist. Obama, however, might have the leeway to push through a relatively liberal nominee.
Their backgrounds and past statements offer a glimpse of how they would approach the search for a new justice:
Obama was the first black president of the Harvard Law Review, a post equivalent to editor in chief. He taught law for 12 years at the University of Chicago. In his 2006 book, The Audacity of Hope, Obama devoted a chapter to the Constitution. He said he believes it is "not a static but rather a living document, and must be read in the context of an ever-changing world."
He opposed Alito, an appeals court appointee of the first President Bush who had voted against abortion rights and narrowly construed job-bias law.
A year earlier, Obama opposed Roberts for chief justice. Roberts, an appeals court judge appointed by President Bush, had voted to uphold the Bush plan to try Guantanamo detainees before a military tribunal. As a lawyer in the first Bush administration, Roberts had argued against Roe v. Wade.
When Obama voted against Roberts in fall 2005, he suggested he wanted a certain personal character in a jurist. The toughest cases, Obama said, "can only be determined on the basis of one's deepest values ... and the depth and breadth of one's empathy. ... (The) critical ingredient is supplied by what is in the judge's heart."
Obama has lauded former California governor and Chief Justice Earl Warren as someone who dealt wisely with societal problems and suggested he could seek a person with broad experience beyond the law.
Harvard University law professor Cass Sunstein, one of Obama's top advisers, says Obama's background would put him at the center of the selection process.
"Obama is a specialist in constitutional law of the sort we haven't seen in the White House in a very, very long time," said Sunstein, whose credentials and connections could put him on an Obama short list of potential nominees.
Outside analysts such as Dorf predict Obama would turn to women for early vacancies to bring the court, which has only one woman (Ginsburg), more in line with women's representation in the general population.
Eleanor Acheson, who as assistant attorney general for Clinton helped nominees navigate their confirmations, predicted Obama and Biden also would seek diversity of experience. All of the current justices came immediately from lower-court posts.
Acheson believes it "very unlikely" that Obama and Biden would believe nominees need long tenure as a lower-court judge.
"I think they would be looking for someone with a more varied experience," she says.
During Biden's chairmanship of the Judiciary Committee from 1987-95, ideology — more than diversity — was Topic A.
He voted against Thomas and for Anthony Kennedy, the conservative in the middle of the court, as well as for the more liberal justices David Souter, Ginsburg and Stephen Breyer. Biden also helped torpedo President Reagan's 1987 nomination of Robert Bork, who narrowly interpreted the Constitution's protections for privacy and due process of law. Most recently, Biden opposed Roberts and Alito.
At the vice presidential debate this month, Biden said he fought the Bork nomination because he suspected that if Bork had been approved, "there would be a lot of changes that I don't like and the American people wouldn't like, including ... Roe v. Wade to issues relating to civil rights and civil liberties."
On the campaign trail, McCain blasts judges who he says "have taken it upon themselves to ... rule on matters that were never intended to be heard in courts or decided by judges."
Yet, he previously voiced more moderate views.
In May 2005, after months of Democrats blocking lower-court Bush nominations, McCain took the lead in a 14-senator bipartisan group to end the stalemate. Their compromise led to votes on three controversial appeals court nominees but ended the hopes of a few others who would have faced endless debate.
The deal drew scorn from conservatives, including Jan LaRue, chief counsel of Concerned Women for America, who called the pact foolish and referred to McCain and the six other Republicans as "the seven dwarfs (who) have handed the filibuster key" to Senate Democrats.
Since then, McCain has tried to reassure conservatives he would favor judges on the right, who would be "immune to flattery and fashionable theory."
"He is very, very committed to the notion that judges have to interpret the Constitution and not try to rewrite it," says Olson, who objects to Obama's reference to the "empathy" of judges.
"That's outside the law," Olson says.
During a speech about the judiciary last May, McCain said, "I will look for people in the cast of John Roberts, Samuel Alito, and my friend the late William Rehnquist — jurists of the highest caliber who know their own minds and know the law, and know the difference."
McCain voted for Clinton appointees Ginsburg and Breyer, plus the five GOP high-court appointees since he was first elected to the Senate in 1986.
McCain's running mate, Palin, apparently has not followed the court closely.
When CBS' Katie Couric asked her last month what decisions other than Roe v. Wade she disagreed with, Palin answered generally and somewhat awkwardly, without specifying any other decision.
Yet, in her home state, Palin has been passionate about the most fractious topics that come before the court, perhaps more so than any other recent vice presidential candidate. Besides opposing abortion rights, she has endorsed teaching creationism — the theory that all of life was created by God — along with evolution in schools.
Her nomination drew immediate approval from leaders of the right-wing base, including the Family Research Council. She has invoked God on public occasions and suggested she does not believe in a high wall to separate church and state.
Notre Dame law professor Richard Garnett, a McCain legal adviser, says Palin's conservatism appeals to the GOP base yet adds, "Sen. McCain on his own has a pretty long and consistent anti-abortion record. He wouldn't need shoring up from the vice president."
McCain said in the most recent debate, "We have to change the culture of America. Those of us who are proudly pro-life understand that."
Last year, Palin condemned the Alaska Supreme Court for striking down a state law requiring girls 16 and under to get parents' consent before obtaining an abortion. The court noted that parental consent, unlike parental notification laws, can mean "a veto" of the abortion right.
In a statement after the ruling, nine months before she would be tapped by McCain, Palin struck a theme similar to his campaign rhetoric: "Our court is out of step with mainstream judicial decisions and our citizens. This decision is clearly a case of legislating from the bench."