Former Illinois Gov. Rod Blagojevich wants to subpoena President Obama to testify in his corruption trial, an outcome experts say is highly unlikely, but not without precedent.
A computer glitch has made public redacted documents, in which the former governor alleges that Obama was actively engaged in the process to pick his Senate successor.
Blagojevich, indicted last year on 16 felony counts, does not accuse the president of criminal wrongdoing, but says only Obama can clarify conflicting stories -- from two government witnesses -- surrounding the processes to appoint a successor.
The White House said it would not comment on an ongoing investigation.
Experts said it was unlikely the president would be called to testify and even less likely that he would do so publicly in open court.
"It's unusual, but far from unprecedented, for a president to provide testimony, albeit at a physical distance from the actual court proceedings," said presidential historian Richard Norton Smith, former director of five presidential libraries.
The first sitting president called to testify was Thomas Jefferson. In 1807, Jefferson was called to testify in the treason trial of Aaron Burr, Jefferson's former vice president.
Jefferson invoked executive privilege and refused to testify, setting a precedent invoked by Richard Nixon, who resigned in 1974 after the Supreme Court ruled he would be required to turn over White House recordings pertaining to the Watergate scandal.
"Gerald Ford gave videotaped testimony in the criminal trial of a woman who had attempted to shoot him. And Ronald Reagan testified after leaving office in matters related to the Iran-Contra affair," Smith said.
"Twice George W. Bush invoked executive privilege to avoid turning over documents, or having aides testify once in 2001, ironically enough, to prevent some Clinton-era documents generated by Janet Reno's Justice Department from reaching Congress; a second time, in response to a congressional probe of the Bush White House over alleged political interference in the firing of several U.S. attorneys," Smith said.
That dispute ultimately was resolved through negotiations with Congress, which led to Karl Rove testifying behind closed doors.
A motion filed by Blagojevich's attorney asserts that Obama should join the ranks of sitting presidents who have been compelled to testify because comments he made last year contradict statements to federal prosecutors made by a labor union president and a candidate for the seat.
"There are two conflicting stories and the defense has the right to admit evidence that contradicts the government's claims," the motion said.
The redacted information, found when the information was cut and pasted off a court Web site, quotes several witnesses saying a labor union official said he had a conversation with Obama on Nov. 3, 2008. In the alleged conversation, Obama is said to have expressed hope that Blagojevich would choose an unnamed "Senate Candidate B," widely believed to be White House adviser Valerie Jarrett, an old friend of the president.
The document quoted the unnamed labor union official as telling FBI agents and prosecutors that Obama thought Senate Candidate B "would be a good senator for the people of Illinois and would be a candidate who could win re-election."