Brady and Giglio Disclosure
Rule
The Due Process Clause requires prosecutors to disclose to the defense all material evidence that is favorable to the defendant. This obligation arises from Brady v. Maryland (1963) and its progeny. Giglio v. United States (1972) extends Brady to impeachment evidence affecting the credibility of government witnesses.
Elements / Requirements
A Brady violation is established when:
- Favorable — the evidence is exculpatory (tends to negate guilt or reduce punishment) or impeaching (undermines the credibility of a prosecution witness)
- Suppressed — the prosecution failed to disclose it; good faith is irrelevant — it does not matter whether the suppression was intentional or inadvertent, or whether the evidence was in the hands of the police rather than the prosecutor (the prosecution team is a unit)
- Material — there is a reasonable probability that, had the evidence been disclosed, the result of the proceeding would have been different (Strickler v. Greene)
Materiality Standard (Kyles)
Kyles v. Whitley (1995) clarifies materiality:
- Materiality is assessed cumulatively, not item by item — the court looks at the combined effect of all suppressed evidence
- A “reasonable probability” does not mean the defendant would more likely than not have been acquitted; it means the suppression undermines confidence in the verdict
- The prosecution has an affirmative duty to learn of favorable evidence known to others acting on the government’s behalf (police, forensic labs)
Giglio — Impeachment Evidence
Giglio v. United States (1972): promises of leniency or immunity made to a government witness must be disclosed. Any deal, benefit, or inducement offered to a cooperating witness is Giglio material. This includes:
- Cooperation agreements and plea deals
- Payments or relocation assistance to informants
- Prior bad acts or criminal history of key witnesses
- Prior inconsistent statements by government witnesses
Timing
The Constitution requires disclosure in time for the defendant to make effective use of the evidence. Courts have generally required pre-trial disclosure of Giglio material; the timing of exculpatory evidence disclosure may vary. Federal practice (DOJ policy) requires prompt disclosure upon discovery.
Remedy
A Brady violation ordinarily requires a new trial. The conviction is vacated if the suppressed evidence was material.
Policy
The Brady doctrine reflects the prosecutor’s unique role as “minister of justice” — not merely an adversary but an officer of the court with obligations to ensure a fair trial. The materiality limitation was designed to avoid converting every disclosure failure into automatic reversal, but critics argue it is too deferential to the prosecution because it is assessed in hindsight.
Key Cases
- Brady v. Maryland (1963) — foundational case; Due Process requires disclosure of exculpatory evidence
- Giglio v. United States (1972) — extends Brady to impeachment evidence; promise to witness must be disclosed
- Kyles v. Whitley (1995) — cumulative materiality standard; prosecution team includes police; affirmed conviction reversed
- Dennis v. United States — defendant’s right to access grand jury materials for impeachment purposes
- People v. Garrett — state court application; illustrates systemic Brady failures