The International Criminal Court (ICC) overturned the conviction for war crimes and crimes against humanity of the former vice president of the Democratic Republic of the Congo, Jean-Pierre Bemba.
Bemba was convicted in 2016 of the crimes committed in the neighboring Central African Republic (CAR) between 2002 and 2003.
He was accused of not preventing his rebels from killing and raping.
But a judge has now said that he can not be held responsible for his actions.
Christine Van den Wijngaert also said that the judges in the 2016 case had not taken into account their attempts to stop the crimes once they became aware that they were taking place.
The decision to revoke the sentence of 18 years was greeted with cheers from his followers in the gallery.
But human rights group Amnesty International said it was a “huge blow” for the victims of a “terrifying campaign of rape and sexual violence,” as it urged the authorities to redouble their efforts to prosecute those who carried out the campaign.
ICC prosecutor Fatou Bensouda described the decision as “regrettable and troubling”.
Prior to Friday’s decision, the ICC had issued verdicts in six cases, with nine people convicted and one acquitted, according to its website.
More than 5,000 survivors participated in the Bemba trial, said Amnesty international justice chief Solomon Sacco.
“For these brave individuals, as well as thousands of other victims in CAR, the pursuit of truth, justice and reparations will continue,” he added.