As for politicians, most recently, retired Justice Sandra Day O'Connor had held elected office in her home state of Arizona, though she was a judge there before her move to Washington. Several decades before O'Connor, President Eisenhower tapped another politician, Earl Warren, to serve as Chief Justice.
At the time, Warren was serving his third term as California governor, and had five years earlier joined the ticket of Republican presidential candidate Thomas Dewey, who lost the election to Harry Truman.
But even if Obama looks to the political world to fill the post, there's no guarantee that the candidate would want to trade a life of legislation, press conferences and public debate for one that requires the parsing of legal minutiae and relative obscurity.
Weeks before he announced his retirement last month, Souter, who was known to loathe the Washington scene, told an audience that he had to give up outside interests each October until June. He compared it to a "sort of annual intellectual lobotomy" -- not exactly the lifestyle a politician or other public figure might relish.
The question of how politicians would approach one of their own kind nominated to the Supreme Court remains to be seen, given their propensity to debate an issue, including the fitness of a candidate for a top post in the federal government.
Just days after Souter tendered his retirement, the chairman of the Senate Judiciary Committee, Sen. Patrick Leahy, D-Vt., pointed out the opportunity to add more racial and gender balance to the court, as its current roster includes seven white men, one white woman and one black man.
"I would like to see certainly more women on the court. Having only one woman on the Supreme Court does not reflect the makeup of the United States. I think we should have more women. We should have more minorities," Leahy said on "This Week with George Stephanopoulos."
Leahy, whose committee holds confirmation hearings for Supreme Court nominees, also said he'd like to see more justices from "outside the judicial monastery" -- people who have life experience that didn't necessarily include donning a black robe.
But Leahy's counterpart on the panel disagrees.
Sen. Jeff Sessions of Alabama, the top Republican on the Senate Judiciary Committee, has said he believes Obama should choose a judge as his Supreme Court nominee.
"There are a lot of people who have experience in the world, but I wouldn't think they would be a Supreme Court justice," Sessions told the Wall Street Journal.
Another Republican on the committee, Sen. Orrin Hatch of Utah, questioned the qualifications Obama has laid out, specifically the notion of an empathetic judge.
"It's a matter of great concern, if he's saying that he wants to pick people who will take sides," Hatch said earlier this month on "This Week."
"He's also said that a judge has to be a person of empathy -- what does that mean? Usually that's a code word for an activist judge."
Obama has stated that he wants a nominee to be confirmed by the start of the court's October term, so the lawmakers should have their chance to decode and debate soon enough.