Addressing questions on whether he had authority to bring the case against Libby, Fitzgerald said, "I was appointed to investigate violations of law … Any crimes related to the disclosure" of the name of Valerie Plame, the former undercover CIA operative who's identity became public in 2003.
In documents filed with the court Tuesday, special prosecutor Patrick Fitzgerald urged Walton to send the former White House aide to prison promptly. A judge has discretion to allow a defendant, whose conviction stands a good chance of being overturned, to remain free during the appeals process. Fitzgerald argued it was unlikely the conviction would be overturned.
But Libby's legal team said its client should stay out of prison through the appeal.
In a motion filed Wednesday, Libby's team also argued that former Bush administration official David Safavian, who was convicted last year as part of the scandal involving former lobbyist Jack Abramoff, was given the same allowance.
"Mr. Libby has met his burden and is entitled to release pending appeal. As noted in our motion, David Safavian, who was convicted of obstruction and false statements, was recently held to be entitled to release pending appeal by a court in this district," the motion noted.
Safavian was the chief of staff at the General Services Administration.
The defense team's argument stemmed from the basis of its appeal -- attorneys say Judge Walton did not allow the testimony of a memory expert during the trial, and that certain exhibits and statements made by NBC News anchor Tim Russert, the prosecution's key witness, were not presented to the jury.
Libby attorney Ted Wells insisted after the March conviction that his client is "totally innocent;" the defense team maintained that Libby had a spotty memory, and should not have been convicted because of it.
After last week's sentencing, Cheney had warm words for his former aide, calling him a man of "the highest intellect, judgment and personal integrity" in a statement released after the hearing.
In a nod to the pending appeal, Cheney continued, "Speaking as friends, we hope that our system will return a final result consistent with what we know of this fine man."
Cheney's office issued an identical statement Thursday.
There has been speculation that the president could pardon the former aide to the vice president, but after Libby's conviction, White House spokeswoman Dana Perino called talk of a pardon "wildly hypothetical."
After Thursday's ruling, Perino said, "Scooter Libby still has the right to appeal, and therefore the president will continue not to intervene in the judicial process. The president feels terribly for Scooter, his wife and their young children, and all that they're going through."
ABC News' Jack Date, Jon Garcia and Karen Travers contributed to this report.