Chui was charged with war crimes and crimes against humanity in the 2003 deaths of 200 villagers in Bogoro in the Ituri province of the Democratic Republic of Congo. He denied participation in the killings, saying he learned of them after the fact.
The judges, sitting in The Hague, Netherlands, said they will hear arguments about whether to keep Chui detained pending appeal of their unanimous ruling, the court said in a release.
In announcing the court's decision, Presiding Judge Bruno Cotte said the evidence and testimony did not prove beyond a reasonable doubt Chui was the commander of the Lendu combatants from Bedu-Ezekere during the attack against Bogoro. Because of the prosecution couldn't meet the "beyond a reasonable doubt" standard, the judges acquitted Chui.
The judges stressed the decision doesn't mean they doubt crimes were committed in Bogoro nor doubt the suffering endured by its residents, the court said. The Chamber also emphasized failing to convict the defendant didn't mean the court found him innocent, only that there wasn't enough evidence presented to determine a conviction "beyond reasonable doubt."