mental competence

For purposes of determining whether a prisoner may withdraw a certiorari petition, mental competence means 'capacity to appreciate his position and make a rational choice with respect to continuing or abandoning further litigation,' as distinguished from 'suffering from a mental disease, disorder, or defect which may substantially affect his capacity in the premises.

Defined by the Supreme Court in - Rees v. Peyton, 384 U.S. 312.