Gbagbo continues to cling to power despite the U.N. recognizing rival Alassane Ouattara as the winner of the Nov. 28 presidential run-off election. Gbagbo's suit, filed in the Economic Community of West African States' Court of Justice in Abuja, Nigeria, asks judges to void decisions by the regional bloc that recognized Ouattara as the winner.
The regional bloc, known as ECOWAS, has been considering whether to use military force to oust Gbagbo. Lawyer Mohamed Lamine Faye, who represents Gbagbo, said ECOWAS' decision "violates the supremacy" of the nation's constitutional council.
Ivory Coast has been gripped by a political crisis since the election. An electoral commission said Ouattara won and the U.N. supervised the election and certified the result. The constitutional council later overturned the results and declared Gbagbo the winner, after invalidating nearly 600,000 votes in pro-Ouattara areas.
"We are asking the court to hold that these pronouncements are illegal," Faye told journalists Monday after filing the suit. "If they are illegal, they are null and void. They should suspend any action in respect to these pronouncements."
Obii Onuoha, an ECOWAS lawyer, said she had no instructions from the bloc about the lawsuit as it was formally filed during the court's open session.
Both Gbagbo and Ouattara have been sworn in as president and have set up competing governments in an attempt to wrestle control of the country from each other. Ouattara has been endorsed as president by the United States, European Union, African Union, former colonial power France and a host of other countries and international organizations. Gbagbo retains control of the army, police and civil service.
At least 290 people have been killed in postelection violence, and more than 30,000 have fled to neighboring Liberia, the U.N. said.