The United States Supreme Court reversed the murder conviction of a Louisiana man and granted him a new trial, finding that the the prosecutor had withheld evidence that could have supported his defense at trial that could have cast doubt on the credibility of prosecution witnesses. This case, Weary v. Cain, is notable because the SJC expanded upon the principle concerning violations of a defendant’s due process rights when the prosecution withholds material evidence.
Under the rule pursuant to Brady v. Maryland, the suppression by the prosecutor 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. In Weary v. Cain, the SJC held that the defendant does not need to establish that “more likely than not” that he would have been acquitted if the withheld evidence had been admitted. Rather, the defendant claiming a “Brady violation” need only show that the evidence is sufficient to “undermine the confidence” in the verdict.