A subpoena requires the person therein named to appear and attend before a court or magistrate at the time and place, to testify as a witness. Under the Uniform Rules of Criminal Procedure, the subpoena must state the name of the court and the title, if any, of the proceeding. It must command each person to whom it is directed to attend and give testimony. The time and place must be specified. The rules governing civil and criminal procedure in federal court provide for the subpoena of witnesses, and specify the form and requisites thereof. Appearance of writ, detainees, and prisoners as witnesses In the American system there is a fundamental right to be heard in due process of law. This is defined in the Fourteenth Amendment of the United States Constitution. A necessary requisite of due process of law is the opportunity to be heard, in a manner which is meaningful, in front of a forum which has an open mind, and is willing to listen to evidence. Adequate notice and an opportunity to confront adverse witnesses must be afforded. As a general rule, independent of statutory considerations, the writ of habeas corpus ad testificandum under American law may be resorted to for the purpose of removing a person confined in a jail or prison to enable him to testify as a witness. The issuance of such a writ lies within the sound discretion of the court, or the judicial officer having the power to compel the attendance of witnesses. Relevance and materiality are of consideration in such matters. The constitutional right of an accused to compulsory process for obtaining witnesses does not necessarily extend to compelling the attendance of person in prison. This right is not violated by a statute which makes the right to the production of a witness confined in prison upon the discretion of the court. The Uniform Rendition of Prisoners as Witnesses in Criminal Proceedings Act provides by way of reciprocity between state for the summoning of a prisoner in one state to appear and testify as a witness in another. This is accomplished by way of a court order which specifies terms and conditions, and a determination and certification that the witness is material to a pending criminal proceeding. The Uniform Act defines a "witness" as a person who is confined in a penal institution in any state and whose testimony is desired