Lawyers for Rep. John P. Murtha will appeal a recent ruling advancing a defamation lawsuit brought against the Pennsylvania Democrat by a U.S. Marine under investigation for killing Iraqi civilians.

Justice Department lawyers representing Murtha on Nov. 16 filed notice that they planned to appeal a federal district court judge’s Sept. 28 ruling allowing the lawsuit to proceed and ordering Murtha to give sworn testimony in the case.

Marine Staff Sgt. Frank Wuterich sued Murtha in August 2006, accusing the 17-term congressman of defaming him during a news conference last year on the Nov. 19, 2005 killings of Iraqi civilians in Haditha.

Wuterich charges that Murtha “publicly and falsely” accused him and other Marines involved in the Haditha incident of “cold-blooded murder and war crimes” and of attempting a cover-up, according to court documents.

Military prosecutors initially charged four enlisted Marines — including Wuterich — with murder and accused four officers of dereliction of duty for failing to adequately investigate the incident.

Charges against four Marines have been dropped and two others will face court-martial, but not for murder.

After a hearing that concluded Sept. 6, an investigating officer recommended Wuterich face court-martial for negligent homicide. Marine Lt. Gen. James Mattis, the commander charged with court-martial authority in the case, has yet to decide whether he will stand trial.

Murtha meanwhile had been ordered to sit for a deposition Nov. 27 to help determine whether he was acting in his official capacity as a U.S. government employee when he made the Haditha comments, as his lawyers have argued.

If the court determines Murtha indeed was acting in his official capacity, the U.S. government could be substituted as the defendant — a move that would effectively neuter the case because the federal government cannot be sued for libel.

But Wuterich’s lawyer, Mark S. Zaid, said Monday that the deposition now likely will be delayed, pending a determination from the U.S. Court of Appeals for the District of Columbia Circuit. The court will have to determine whether it has the jurisdiction to hear Murtha’s appeal at this stage or if it should wait until a lower court determine’s the fate of Wuterich’s lawsuit.

U.S. Attorney Darrell C. Valdez, who represents Murtha, did not respond to a request for comment.