The ruling read in court by Presiding Judge Piotr Hofmanski puts more pressure on Ivory Coast officials to hand over Simone Gbagbo for prosecution in The Hague.
The ruling said that the case against Gbagbo is admissible because Ivory Coast had not proved, at the time it challenged the case's admissibility, that Ivorian authorities were investigating her for the same allegations as those she faces in The Hague. The International Criminal Court is a court of last resort that can only take action when a government cannot or will not prosecute a suspect.
The International Criminal Court appeared to leave open the possibility of Ivorian authorities filing a fresh challenge based on that conviction, saying in a statement that under the court's founding treaty, "in exceptional circumstances, the Court may grant leave for a challenge to be brought more than once."
The ICC issued an arrest warrant for Gbagbo in 2012, the first time the court had filed charges against a woman. It said evidence suggested she was a key member of the inner circle surrounding her husband, former president Laurent Gbagbo, which planned attacks on his political opponents after he lost the 2010 election to his opponent Alassane Ouattara.
It wasn't immediately clear if authorities in Ivory Coast will now hand over Gbagbo, whose husband already is in The Hague awaiting trial on similar charges.
Human Rights Watch's senior international justice counsel, Param-Preet Singh, said today's ruling "eliminates any doubt" about Ivory Coast's "duty to surrender Simone Gbagbo to The Hague.