Twelve prominent law professors are questioning whether Special Counsel Patrick Fitzgerald had constitutional authority in the CIA-leak trial in which former White House aide I. Lewis “Scooter” Libby was sentenced to prison this week.

The push comes as Libby’s attorneys, who are making the same argument, prepare to appeal his 2 1/2-year sentence.

“The constitutional issue to be raised on appeal is substantial,” conservative Robert Bork, liberal Alan Dershowitz and 10 other professors wrote in their nine-page brief, filed Thursday at U.S. District Court in the District of Columbia.

“To our knowledge, the special counsel appears to occupy virtually a ‘class of one’ in the history of special prosecutors,” the professors wrote.

Yesterday, Judge Reggie B. Walton of U.S. District Court agreed to consider the legal argument as part of Libby’s request for bail while the case is appealed.

But in a sharp rebuke to the professors, Walton sarcastically called it “an impressive show of public service” that such a group of distinguished lawyers would rush to help a criminal defendant - and questioned whether they would do the same for others who lacked financial means for brilliant legal aid.

“The court will certainly not hesitate to call for such assistance from these luminaries, as necessary in the interests of justice and equity, wherever similar questions arise in the cases that come before it,” Walton wrote in his one-page order granting the request to consider the constitutional argument.

The professors say that Fitzgerald may have been given too much power, with too little accountability, because he was not appointed by the president or approved by the Senate. Moreover, they say, Fitzgerald was exempted from complying with Justice Department policies - even though he was appointed by the attorney general.

Libby could have a better chance of release if his supporters can convince the judge that the constitutional question is a close call.

Walton last year rejected the same argument, saying then that Fitzgerald’s powers are limited because he can be removed by the Justice Department.

Fitzgerald was appointed special counsel in 2003 by his former colleague and friend, then-Deputy Attorney General Jim Comey.

John Ashcroft, who was serving as attorney general, had recused himself from the investigation because of his White House contacts.