In United States v. Agurs, the U.S. Supreme Court held for the first time that criminal prosecutors have a constitutional duty to voluntarily disclose exculpatory evidence to a defendant even when the defense doesn't request such evidence. The Court, however, limited the scope of this new obligation by narrowly defining the category of material evidence to which it applies. It held that the duty arises only when the exculpatory evidence is so material that had it been disclosed, its use at trial would have created a reasonable doubt of the defendant's guilt that did not otherwise exist.
Respondent Agurs was convicted of second degree murder in the U.S. District Court for the District of Columbia. At trial she asserted that she had acted in self-defense in the knife slaying of the victim. The evidence at trial showed that the victim had been carrying two knives, one of which was the murder weapon, immediately before he was killed. After the respondent was convicted, her attorney discovered that the prosecutor had been aware of the victim's criminal record before the trial. The victim had a history of convictions for violent crimes, including assault and carrying a deadly weapon. Agurs moved for a new trial on the ground that the victim's prior criminal record supported her claim of self-defense and thus should have been disclosed by the prosecution.
Knight, James K. Jr.
"'Materiality' Limits Prosecutors' Duty to Disclose Exculpatory Evidence to Defense,"
Mercer Law Review: Vol. 28:
1, Article 25.
Available at: https://digitalcommons.law.mercer.edu/jour_mlr/vol28/iss1/25