Discovery

Under COMMON LAW, there was no discovery in criminal cases. As of the early 2000s, in federal and many state criminal prosecutions, only limited discovery is permissible, unlike the full disclosure of information available in civil actions. Limited discovery prevents the possible intimidation of prosecution witnesses and the increased likelihood of perjury that might result from unabridged disclosure. The obligation of the prosecutor to prove the case BEYOND A REASONABLE DOUBT, the possibility of an unconstitutional infringement upon a defendant's right against self-incrimination, and violations of the attorney-client privilege pursuant to a client's RIGHT TO COUNSEL also hinder complete discovery. A defendant who requests particular documents from the government may be required to submit items of a similar nature to the government upon its request for discovery. The disclosure of false evidence or the failure of the prosecution to disclose documents that are beneficial to the defense can result in a denial of DUE PROCESS OF LAW.

The federal Jencks Act (18 U.S.C.A. § 3500 [1957]) entitles a defendant to obtain access to prosecution documents necessary to impeach the testimony of a prosecution witness by showing that the witness had made earlier statements that contradict present testimony. Theoretically, the defense cannot receive the statements until the witness has finished testimony on direct examination, but, in practice, such statements are usually available before then. Many states have similar disclosure rules.