A US Marine sentenced to 11 years in prison for the 2006 murder of an Iraqi civilian has had his conviction overturned after a military court ruled his rights had been violated.

Sergeant Lawrence Hutchins, 29, was jailed six years ago after a court martial found him guilty of orchestrating the murder of a 52-year-old Iraqi man in the town of Hamdania.

Hutchins was convicted of leading an eight-strong squad which kidnapped the father of 11 from his home in a night-time raid, frogmarched him to a ditch and shot him.

The group then placed an AK-47 and a shovel beside the dead man's corpse to make it look as if he had been shot while planting a roadside bomb.

Several soldiers involved in the incident, who received lesser sentences for their roles in the killing, had implicated Hutchins.

However the US military's highest court, The Court of Appeals for the Armed Forces, tossed out Hutchins's conviction after agreeing his constitutional rights had been violated early in the investigation.

Lawyers for Hutchins argued investigators had erred when the Marine was held in solitary confinement without access to a lawyer for seven days.

Hutchins later signed a confession on May 19, 2006, following his detention, a submission used to secure his conviction.

However the military court ruled the confession had been obtained illegally and quashed the verdict.

"We therefore reverse the decision of the CCA (Navy-Marine Corps Court of Criminal Appeals), set aside the findings and the sentence, and return the case to the Judge Advocate General of the Navy," the court ruled.

"It was an error for the military judge to admit the statement made by Hutchins on May 19, 2006.

"Notwithstanding the other evidence of Hutchins's guilt, there is a reasonable likelihood that the statement contributed to the verdict."

The US Marines must now decide whether to re-try Hutchins or appeal the decision to the Supreme Court.

The case has seen various twists and turns since Hutchins's conviction. His original sentence of 15 years was slashed to 11 years, and the conviction was overturned once before in 2010 but later reinstated.