The Ohio Supreme Court has overturned the death sentence of a man who argued he cannot be executed because he is mentally retarded.

The high court ruled unanimously Wednesday in Columbus, Ohio, in favor of convicted killer Clifton White.

The Ohio court based its decision on a 2002 ruling by the U.S. Supreme Court that said executing the mentally retarded violates the Constitution's ban on cruel and unusual punishment.

A court elsewhere in Ohio has been hearing testimony on the constitutionality of the state's lethal injection method of execution.

Lethal injection executions are on hold nationally while the U.S. Supreme Court considers a challenge in a case from Kentucky.