A Florida college professor who pleaded guilty to aiding Palestinian Islamic Jihad, Sami Al-Arian, is making a fresh attempt to persuade a federal appeals court to order an end to his imprisonment for failing to testify before a grand jury.

Al-Arian’s latest bid for freedom came in a legal filing last week, in which he asked the full, 12-judge bench of the Richmond-based 4th Circuit Court of Appeals to overturn a three-judge panel’s decision last month upholding his jailing for refusing to answer questions before a grand jury investigating Northern Virginia Islamic charities.

This week, the Supreme Court is scheduled to take up a separate legal petition in which the Kuwaitiborn professor is challenging the basis for the 57-month prison sentence he received after entering a guilty plea last year on charges of providing assistance to a designated terrorist group. With credit for time served since his arrest in 2002, Al-Arian could have been released and deported as soon as Friday. However, a judge put Al-Arian’s criminal sentence on hold while he serves up to 18 months for civil contempt.

In seeking so-called en banc review by the 4th Circuit, an attorney for Al-Arian, C. Peter Erlinder, argued that the former professor is entitled to hold the government to an oral promise federal prosecutors in Florida allegedly made not to seek his assistance in other cases, including the Virginia investigation.

“Insofar as there exists any ambiguity or imprecision with respect to the terms of the government’s admitted oral modification of the plea agreement, that language must be construed against the government and in favor of Dr. John Doe,” Mr. Erlinder, a professor at William Mitchell College of Law in St. Paul, Minn., wrote. Al-Arian, who taught computer science at the University of South Florida, is referred to by a pseudonym in the 4th Circuit’s public records, though his identity is evident from the filings.

Al-Arian’s legal argument has made little headway in the courts. In addition to the unanimous 4th Circuit panel, it was also rejected by the judge who oversaw Al-Arian’s six-month trial in Tampa in 2005.

That trial resulted in Al-Arian’s acquittal on eight charges and a mistrial on nine others after jurors failed to reach a verdict.

However, the claim that the government turned its back on a promise has won Al-Arian some unusual support. A retired attorney and Jewish activist who has long been critical of Al-Arian, Barry Augenbraun of St. Petersburg, Fla., recently wrote a letter to a local newspaper decrying the government’s tactics in the case.

“I have no truck with Sami Al-Arian. I believe he’s a terrorist and he funded terrorism, but the government made a deal,” Mr. Augenbraun said in an interview last night.

Asked why he was speaking up for Al-Arian, Mr. Augenbraun, who is co-chairman of his local Jewish Community Relations Council and a fund-raiser for the Jewish Federation, said, “I can give it to you in two words: Jonathan Pollard. The government did the same thing to Jonathan Pollard that they did to this guy.”

Pollard, a naval intelligence analyst, was sentenced to life in prison in 1987 after pleading guilty to espionage.

In the plea deal, the government agreed not to seek a life sentence for Pollard. However, the judge sentenced Pollard to life after reading an affidavit in which the defense secretary at the time, Caspar Weinberger, said Pollard’s acts did grave damage to national security.

Mr. Augenbraun said a federal prosecutor’s promises should be binding on the entire federal government.

A spokesman for the U.S. Attorney’s office in Northern Virginia, James Rybicki, declined to comment for this article.

After losing 55 pounds, Al-Arian, 49, recently suspended a twomonth hunger strike that he undertook to protest his treatment. “You could see the shape of his skull. You could see the bones of his legs. Everything was very, very thin,” his wife, Nahla Al-Arian, told a Tampa radio station, WMNF-FM. “It was scary.”