The Pennsylvania AO-89 Subpoena to Testify at a Hearing or Trial in a Criminal Case is a legal document that orders a person to appear in court to testify as a witness in a criminal case. The subpoena is issued by the court or a law enforcement agency and can be served upon the person being summoned by law enforcement officers, a process server or by mail. The person being subpoenaed is required to appear and testify at the hearing or trial, and failure to do so can result in legal consequences. The Pennsylvania AO-89 Subpoena to Testify at a Hearing or Trial in a Criminal Case is issued under Rule 102 of the Pennsylvania Rules of Criminal Procedure. There are two types of Pennsylvania AO-89 Subpoena to Testify at a Hearing or Trial in a Criminal Case: the subpoena duces tecum and the subpoena ad testificandum. The subpoena duces tecum requires the person being subpoenaed to bring physical evidence to the hearing or trial, such as documents, records, photographs, or other tangible items. The subpoena ad testificandum requires the person being subpoenaed to appear and testify, but does not require any physical evidence.