"Petition for discovery" is a document related to a legal proceeding in the United States in which a person involved in a criminal case requests information or evidence from the opposing party. The purpose of such a petition is to obtain materials that may help in the defense of the accused or point to the guilt of the accused person. Under the discovery procedure, parties in a legal case have the right to obtain certain information from each other before trial. This information may include documents, recordings, witness lists, and so on. Everything depends on the specifics of each case and the requirements of each party.

American Heritage Dictionary: 3. Law The compulsory disclosure to the opposing party of factual information or documents relevant to a lawsuit prior to trial.
Tal vez en Argentina acepten el término en inglés "discovery" con una explicación entre paréntesis.