In a major victory for the highest-ranking Marine accused of crimes in the deaths of two dozen Iraqi civilians in 2005, a military appeals court has upheld the dismissal of dereliction of duty charges against him.

The unanimous decision by the United States Navy-Marine Corps Court of Criminal Appeals in Washington supports a finding that improper command influence unlawfully tainted the case against Lt. Col. Jeffrey Chessani.

"Praise God and amen," was the reaction of the 43-year-old Chessani when informed of the ruling by one of his attorneys, Brian Rooney.

"He was very happy and appreciative," Rooney said.

The ruling published on the court's Web site Tuesday also might be used in the only other unresolved case among eight Camp Pendleton Marines initially charged with wrongdoing at Haditha, Staff Sgt. Frank Wuterich.

Four officers and four enlisted men from the base's 3rd Battalion, 1st Marine Regiment commanded by Chessani were charged in December 2006 with crimes at Haditha, the largest war-related prosecution of Marines since the 2003 invasion of Iraq. The charges came after investigators could not tie any of the slain Iraqis to the bombing that preceded the killings or the insurgency.

Despite initial charges that included murder against some of the accused, the Marine Corps has failed to win a single conviction. Including Chessani, seven of the eight men charged have been exonerated through a later dismissal or withdrawal of charges or a not-guilty finding at trial.

Wuterich remains at the center of the case. It was after a roadside bombing that killed one of his men that Wuterich led an assault that resulted in the deaths of the Iraqi men, women and children, most of whom were inside one of three homes his troops stormed.

Last June, the military judge in Chessani's case, Col. Steven Folsom, dismissed the dereliction charges that alleged Chessani failed to order a full-scale investigation into the Nov. 19, 2005, killings.

Folsom found that a legal adviser to then-Lt. Gen. James Mattis, who was overseeing all the Haditha prosecutions, should not have had any role in the case.

The adviser, Col. John Ewers, had investigated each of the accused Marines and was listed as a prosecution witness. Folsom ruled Ewers' presence at meetings between Mattis and prosecutors created an unacceptable perception of unlawful command influence.

The three Marine officers who make up the Navy-Marine Corps Court of Appeals agreed.

"It is the duty of the military judge to act as the last sentinel and protect the court-martial from the pernicious effects of unlawful command influence," the appeals court wrote.

The Marine Corps can challenge the finding to the Court of Appeals for the Armed Forces in Washington, a panel composed of five civilians. Lt. Col. Dave Griesmer, a Marine Corps spokesman, said no decision on a possible appeal has been made.

The service also can seek a new investigation of Chessani's role at Haditha. If it takes that course, it has to find a new convening military authority outside of Camp Pendleton who would first have to weigh whether reopening the case is justified.

Rooney said taking that course would not serve justice nor Chessani, who remains on duty at Camp Pendleton.

"We have always said that we have had the luxury of defending a truly innocent man and we remain confident the facts are on our side," Rooney said. "I wouldn't be surprised if they do appeal, but I do believe it would be a waste of military resources and taxpayer dollars.

"The Marine Corps needs to move on and Lieutenant Colonel Chessani needs to move on."

Wuterich's attorneys have said they will ask for a dismissal of the nine counts of manslaughter and related charges against their client on the basis of the unlawful command influence found in Chessani's case. Wuterich was one of the men initially accused of murder.

Gary Solis, a former Marine legal officer and military law expert, said he believes Wuterich now has "a ready-made, trial-ending argument."

And even though no Haditha defendants have been convicted, Solis said that doesn't mean the Marine Corps shouldn't have prosecuted.

"The result might suggest it was an ill-considered case from the outset, but I don't believe that," he said. "Haditha was an event that could not have been overlooked because there were too many incontrovertible facts that indicated the possibility, if not the probability, of wrongdoing."

Contact staff writer Mark Walker at (760) 740-3529 or mlwalker@nctimes.com.