In Brady v. Maryland (1963) 373 U.S. 83, 87, the Supreme Court of the United States held "that the suppression by the prosecution of evidence favorable to an accused upon request violates due process where the evidence is material either to guilt or to punishment, irrespective of the good faith or bad faith of the prosecution."
"'The term "Brady Disclosure" is sometimes used to refer to any breach of the broad obligation to disclose exculpatory evidence--that is, to any suppression of so-called "Brady material"--although, strictly speaking, there is never a real "Brady violation" unless the nondisclosure was so serious that there is a reasonable probability that the suppressed evidence would have produced a different verdict. There are three components of a true Brady violation: The evidence at issue must be favorable to the accused, either because it is exculpatory, or because it is impeaching; that evidence must have been suppressed by the State, either willfully or inadvertently; and prejudice must have ensued.' Prejudice, in this context, focuses on 'the materiality of the evidence to the issue of guilt or innocence.' Materiality, in turn, requires more than a showing that the suppressed evidence would have been admissible , that the absence of the suppressed evidence made conviction 'more likely' , or that using the suppressed evidence to discredit a witness's testimony 'might have changed the outcome of the trial' . A defendant instead 'must show a "reasonable probability of a different result."' " (People v. Salazar (2005) 35 Cal.4th 1031, 1042-1043.)