A federal judge is adding the heft of a 30-page legal opinion to his decision last week not to permit a former chief of staff to Vice President Cheney, I. Lewis Libby Jr., to remain free while he appeals his convictions for obstructing the CIA leak investigation.

Judge Reggie Walton’s decision to file a detailed and carefully-reasoned justification for his ruling adds some incline to the uphill battle Libby faces in trying to convince a federal appeals court panel to grant him a stay of his 30-month prison term while his lawyers fight to overturn his conviction. The lengthy opinion could also be viewed as a shot across the bow of the appeals court panel, which is certain to face claims it had more of an eye on politics than law if it chooses to upend Judge Walton’s decision.

In a footnote to the opinion he filed Thursday, Judge Walton said he wanted “to ensure that the Circuit Court has a clear record of this Court’s conclusion and reasoning” in denying the motion to stay Libby’s sentence.

The issue of a stay is politically sensitive for President Bush. If a stay is granted, Mr. Bush can put off a decision about whether to pardon Libby for the duration of the appeal, which could last a year or more. If Libby’s convictions are overturned, there might be no need for a pardon at all.

However, if Libby is denied a stay and must report to jail in the next few weeks, the White House will face intense pressure from Libby’s allies to grant a pardon.

A jury convicted Libby in March on charges of obstruction of justice, perjury before a grand jury, and making false statements to the FBI. All the charges arose during an investigation of the disclosure in the press of the identity of a veteran CIA officer, Valerie Plame. No charges have been brought for the leak itself.

Most of Judge Walton’s new opinion (link: https://ecf.dcd.uscourts.gov/cgi-bin/show_public_doc?2005cr0394-373) is devoted to the argument of Libby’s attorneys that the special prosecutor, Patrick Fitzgerald, was unconstitutionally appointed because he acted without supervision by the Attorney General or any other official confirmed by the Senate. The judge rejects claims by Libby’s legal team that letters giving Mr. Fitzgerald broad discretion to conduct his probe amounted to the kind of unfettered authority that could run afoul of the Constitution’s appointment clause. “They do not confer upon Fitzgerald as Special Counsel the prosecutorial equivalent of James Bond’s license to kill, and are unlikely to be read by any court as a blank check,” the judge wrote. “The Special Counsel was and is clearly a subordinate within the Department of Justice, even if he has not been closely supervised or directed on a day-to-day (or even week-to-week) basis in a manner that might cause his independence and impartiality, so necessary in an investigation of this type, to legitimately be questioned.”

Judge Walton said Mr. Fitzgerald was subject to removal at any time by a senior Justice Department official and his authority could have been circumscribed as well at any point. The judge said it was “resoundingly clear” that Mr. Fitzgerald’s appointment was constitutional under the tests set forth in a 1988 Supreme Court case, Morrison v. Olson, which upheld the constitutionality of an independent counsel appointed under a 1978 law, the Ethics in Government Act. The independent counsel provision expired in 1999, but the Justice Department has appointed special counsels since then from outside the department and from inside, as is the case with Mr. Fitzgerald who is also the top federal prosecutor in Chicago.

In his written ruling, Judge Walton also accepted Mr. Fitzgerald’s claim that the defense engaged in a “talmudic dissection” of the language in the judge’s earlier rulings “in a manner that deprives it entirely of context.”

Judge Walton’s latest opinion could also be seen as a further retort to 12 legal scholars, some of the eminent in the profession, who filed an amicus brief arguing that Mr. Fitzgerald’s appointment raised serious constitutional questions. If that was Judge Walton’s intent, it may have been overkill since the appeals court on Wednesday refused an amicus brief from the same scholars.

Based on the schedule the appeals court set for briefs, it seems that the panel could make a decision as soon as next week on Libby’s request for a stay.

If the court turns him down, he could seek relief from the Supreme Court. Another possibility, first raised on National Review’s Web site, is that Mr. Bush could issue a form of clemency known as a respite, which could have the same effect as a stay.