What is the legal test for overturning a conviction of an accused who is legally incompetent to stand trial?

The conviction of an accused person while legally incompetent to stand trial is a clear violation of the constitutional guarantee of due process. Pate v. Robinson, 383 U.S. 375, 378, 86 S.Ct. 836, 838, 15 L.Ed.2d 815 (1966). If a state trial court does not employ procedures designed to protect against the trial of an incompetent, the resultant conviction must be reversed. See id. at 386-87, 86 S.Ct. at 842-43; see also Drope v. Missouri, 420 U.S. 162, 171-72, 95 S.Ct. 896, 903-04, 43 L.Ed.2d 103 (1975). The trial court's constitutional obligation is discharged by holding a hearing to determine competency. See Pate, 383 U.S. at 387, 86 S.Ct. at 843.