The ruling by the judge, Lt. Col. David M. Jones, comes after a two-day hearing in which defense attorneys claimed that a general who brought the charges was improperly influenced by military investigator Colonel John Ewers.
"There was no improper influence flowing upwards or downwards," Jones stated, reading from a lengthy statement.
"Despite a past personal relationship, the court is persuaded that Ewers did not give the general any legal advice regarding the Haditha case."
Wuterich, who will now stand trial for the killings, showed no emotion during the ruling, sitting at a table with his hands clasped.
His case stems from a bombing that claimed the life of a Marine in Haditha, 260 kilometers (140 miles) west of Baghdad. Many of the victims were unarmed men, women and children.
Citing the lengthy, stellar careers of Ewers and charging General James Mattis, Jones said the pair may have been in meetings together but no evidence was presented to show that they discussed the case or that Ewers offered advice.
"The court must deal in facts, not mere speculation or conjecture," he said.
In fact, Ewers was still in Iraq while most of the information was gathered and the charges were being brought forward, he said.
Wuterich was initially charged with murder, aggravated assault, reckless endangerment, dereliction of duty, and obstruction of justice. The murder charge was later downgraded to voluntary manslaughter by another general.
Mattis and Ewers "had no substantive conversations ever regarding the Haditha case," the judge said.
In hindsight it probably was not a good idea for Ewers to attend meetings with the general where an appearance for impropriety could exist, he said.
"It is reassuring that the generals did their homework in the accused case and did not act as a rubber stamp," the judge said. "In fact the opposite has been exclusively proven."
The Marines said in a press release issued after the violence in Haditha that 15 Iraqis had been killed by the roadside bomb that killed the Marine.
But a subsequent investigation by Time magazine showed most of the dead were killed as Marines swept through three houses near the site of the bombing.
Jones set a trial date of September 13 and Wuterich said he wanted a jury comprised of some enlisted personnel.
For the past three years, Wuterich and a group of supporters have proclaimed his innocence in the media and on the internet.
"We know our son is innocent, we know he has done nothing wrong, we know he was following the 'Rules of Engagement,'" Wuterich's parents Rosemarie and David wrote on a website dedicated to their son's vindication.
"He is a Marine who was doing the job he was trained to do."
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