Discovery in criminal prosecutions (cases) generally refers to (1) the process by which the prosecution (government) gathers evidence to prove its case at trial and (2) the prosecution’s duty to disclose such evidence to the defendant—usually through the defendant’s lawyer or counsel.

The state or federal government’s disclosure of material, exculpatory evidence (tending to disprove the defendant’s guilt) or impeachment evidence (tending to impeach or contradict the prosecution’s witnesses) is part of the Constitutional guarantee of a fair trial and is known as Brady material or a Brady disclosure. See Brady v. Maryland, 373 U.S. 83, 87 (1963); Giglio v. United States, 405 U.S. 150, 154 (1972). Because these are Constitutional obligations, such evidence must be disclosed to the defendant regardless of whether the defendant makes a request for exculpatory or impeachment evidence. Kyles v. Whitley, 514 U.S. 419, 432-33 (1995). But the law does not require the government to disclose such evidence to the defendant before entering into a plea agreement with the defendant. U.S. v. Ruiz, 536 U.S. 622, 629 (2002); Weatherford v. Bursey, 429 U.S. 545, 559 (1977).

The Constitution requires the prosecution to disclose exculpatory and impeachment evidence that is material to a finding of guilt—in other words, when there is a reasonable probability that effective use of the evidence will result in an acquittal. United States v. Bagley, 475 U.S. 667, 676 (1985). Because it is sometimes difficult to determine the materiality of evidence before trial, prosecutors generally must take a broad view of materiality and err on the side of disclosing exculpatory and impeachment evidence. And the disclosure of exculpatory and impeachment evidence extends to law enforcement (police) and other government employees—including employees of agencies other than the prosecuting attorney’s office (U.S. Attorney or District Attorney) such as Child Protective Services.

Some states have laws that go beyond the U.S. Supreme Court’s directives in the Brady case and provide more detailed requirements for the timing and substance of such disclosures. These laws may be located in the state’s court opinions, statutes, or rules of criminal procedure, for example.

In Florida, discovery in criminal prosecutions is governed by both constitutional mandates and state-specific rules. The prosecution is required to disclose evidence that is material to the case, including exculpatory evidence that could prove the defendant's innocence and impeachment evidence that could undermine the credibility of the prosecution's witnesses. This obligation is rooted in the U.S. Supreme Court's decisions in Brady v. Maryland and its progeny, which establish that such disclosures are necessary for a fair trial. Florida's discovery rules are outlined in the Florida Rules of Criminal Procedure, particularly Rule 3.220, which details the prosecutor's duty to disclose information and the process for the defense to discover evidence. The rule mandates that the prosecution must disclose certain information and evidence within 15 days of the defendant's request. This includes witness lists, statements of persons the state intends to call at trial, any written or recorded statements by the defendant, and any material information within the state's possession that tends to negate the guilt of the defendant. The state's obligation to disclose is ongoing and includes evidence gathered by law enforcement and other government agencies. While the U.S. Supreme Court has ruled that the government is not required to disclose exculpatory evidence before entering into a plea agreement, Florida's rules ensure that defendants have access to critical evidence that could influence the outcome of their case.