The reasonable doubt standard is primarily effectuated by jury instructions, but it retains its relevance when the trial judge considers a motion for a directed verdict of acquittal and when an appellate court reviews the sufficiency of the evidence. On federal habeas review of a state conviction for sufficiency of the evidence, to grant relief, the reviewing court must find that "upon the record evidence adduced at the trial no rational trier of fact could have found proof of guilt beyond a reasonable doubt." In a successive, abusive, or defaulted federal habeas review of a state conviction, a defendant claiming "actual innocence" must show that "it is more likely than not that no reasonable juror would have found petitioner guilty beyond a reasonable doubt." "Brady v. Maryland" (1963) is another significant, specific criminal procedural right guaranteed by the due process clauses. "Brady" requires a criminal conviction to be reversed if the government withholds exculpatory (or impeachment) material, within the government's possession, from the defendant, and there is a reasonable probability that, if such material had been disclosed, the result of the proceeding would have been different ("materiality"). "Brady" is a holistic, rather than piece-by-piece, inquiry. Whether the government acted in "good faith" or "bad faith" is irrelevant to "Brady". But, if the defendant cannot prove that withheld evidence would have been exculpatory, because its import is unknown, to obtain relief, the defendant must instead show that the government acted in bad faith. The government is not required to disclose impeachment material prior to plea bargaining. Whether the government must disclose exculpatory material during plea bargaining is an open question. "It has long been accepted that a person whose mental condition is such that he lacks the capacity to understand the nature and object of the proceedings against him, to consult with counsel, and to assist in preparing his defense may not be subjected to a trial" consistent with the Due Process Clause. The "test" is "whether he has sufficient present ability to consult with his lawyer with a reasonable degree of rational understanding—and whether he has a rational as well as factual understanding of the proceedings against him." A state may place the burden on the defendant has to prove incompetence by the preponderance of the evidence, but the state cannot require the defendant to prove incompetence by a higher standard, such as clear and convincing evidence. The right to competence cannot be waived because waivers of constitutional rights are required to be knowing and voluntary.