Which doctrinal rule requires prosecutors to disclose known information that may be used to impeach a witness?

• A. Brady-Giglio Doctrine
• B. Miranda Rights
• C. Jencks Doctrine
• D. Exclusionary Rule

Answer: (A)

The duty to disclose information known to prosecutors that could be used to impeach a witness comes from the Brady-Giglio Doctrine. Brady v. Maryland established that prosecutors must disclose exculpatory evidence favorable to the defense, and Giglio v. United States extended that obligation to impeachment information—details that could undermine a witness’s credibility, such as prior inconsistent statements, dealings, or large character conflicts. Together, they require prosecutors to reveal information that could affect how a witness is viewed by the jury, ensuring the defendant receives a fair opportunity to challenge testimony.

This differs from Miranda Rights, which focus on warnings to suspects about their rights during interrogations. It also differs from the Jencks Doctrine, which governs production of prior statements of government witnesses after they have testified, not the ongoing obligation to disclose impeachment material. The Exclusionary Rule deals with whether unlawfully obtained evidence can be admitted at trial, not with disclosure duties concerning witness credibility.