Brady material is derived from the United States Supreme Court case Brady v. Maryland in 1963. It established a rule that the prosecution has a constitutional duty of due process to disclose material evidence favorable to a defendant. Later, in the State v. Carter case, the court found that such evidence should be “(1) material to the issue and not merely cumulative or impeaching or contradictory, (2) discovered since the trial and not discoverable by reasonable diligence beforehand, and (3) of the sort that would probably change the jury’s verdict if a new trial were granted.”
In practice, if the prosecutor suppresses or fails to disclose evidence that is material to the defendant's guilt verdict or sentence, or influences the “credibility of a witness,” no matter whether the prosecution is of good or bad faith, intentionally or inadvertently, the defendant can use the Brady material to get a new trial. See: United States. v. Bagley. The prosecutor is not required to disclose entire files, but only “impeachment” and “exculpatory evidence” to the defense counsel, regardless of whether the evidence is in their possession or not or whether they are asked to do so or not. To be more specific, the prosecutor has an “affirmative duty” to search their files and the files of law enforcement officers who work on the case for material evidence. As to the defendant, they are required to demonstrate that if such material evidence is disclosed and used effectively, it might “affect the outcome of the trial” or “undermine confidence in the verdict.” See Kyles v. Whitley.
The Brady material has three components: “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” concluded in the Strickler v. Greene case. Once the above elements contend, the Brady violation is established.
[Last updated in June of 2021 by the Wex Definitions Team]