A more thorough explanation:

Reverse Jencks is a term used in criminal procedure. It refers to a written or recorded pretrial statement made by a defense witness that a prosecutor is entitled to have in preparing to cross-examine the witness. This material can be obtained during pretrial discovery and includes a witness's signed or adopted written statement, and transcripts or recordings of the witness's oral statements, including grand-jury testimony.

For example, if a defendant in a criminal case calls a witness to testify on their behalf, the prosecutor is entitled to obtain any written or recorded statements made by that witness before the trial. This is known as reverse Jencks material.

Reverse Jencks material is important because it allows both the prosecution and defense to prepare for cross-examination and to ensure that witnesses are truthful and consistent in their testimony.

• A defendant in a criminal case calls a witness to testify on their behalf. The prosecutor requests any written or recorded statements made by the witness before the trial. This is an example of reverse Jencks material.
• During pretrial discovery, a defense attorney obtains a witness's signed written statement and provides it to the prosecutor. This is an example of reciprocal discovery, which is another term for reverse Jencks material.

These examples illustrate how reverse Jencks material is used in criminal cases to ensure that both the prosecution and defense have access to all relevant information before trial.