The Supreme Court reversed Juan Smith's conviction in an 8-1 decision yesterday (opinion here). The case involved prosecutorial misconduct out of the District Attorney's office in Orleans Parish. The prosecution failed to turn over a detective's notes that contained conflicting statements by the sole eye-witness. (You might recall that the same DA's office was involved in Connick v. Thompson, where last term the Court overturned an $14 million jury award granted to Mr. Thompson after he was acquitted having served 18 years in prison, 14 on death row).
Roberts wrote the opinion, observing:
Under Brady, the State violates a defendant’s right to due process if it withholds evidence that is favorable to the defense and material to the defendant’s guilt or punishment. See 373 U. S., at 87. … We have explained that “evidence is ‘material’ within the meaning of Brady when there is a reasonable probability that, had the evidence been disclosed, the result of the proceeding would have been different.” Cone v. Bell, 556 U. S. 449, 469–470 (2009). A reasonable probability does not mean that the defendant “would more likely than not have received a different verdict with the evidence,” only that the likelihood of a different result is great enough to “undermine confidence in the outcome of the trial.” Kyles v. Whitley, 514 U. S. 419, 434 (1995).
Adam Liptak (NYT) offers more details here.