What is the test for determining whether a defendant is legally incompetent?

Convictions of legally incompetent persons violate due process, and where the evidence raises a bona fide doubt about the defendant's competency, due process requires that a full competency hearing be conducted. Pate v. Robinson, 383 U.S. 375 (1966). However, such a hearing is not required absent a "substantial" or "bona fide" doubt as to the defendant's competence. Hernandez v. Ylst, 930 F.2d 714, 716 (9th Cir.1991). A habeas petitioner is entitled to such a hearing if he presents

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