The Compulsory Process Clause within the Sixth Amendment to the United States Constitution lets criminal case defendants attain witnesses in their favor by way of a court-ordered subpoena.
Though the case was heard in Federal Circuit Court the presiding judge was Chief Justice John Marshall who ordered the papers be issued, invoking the Sixth Amendment.
[6] For example, the Court in Brady v. Maryland used the Due Process Clause to require the prosecution in criminal proceedings to disclose evidence that is favorable to the defendant prior to a trial.
[9]In Washington v. Texas (1967), the Supreme Court held that the Clause barred a state law that made persons charged or convicted as co-participants in a common crime incompetent to testify on behalf of one another.
Chief Justice Earl Warren, who wrote the majority opinion, stated that compulsory process was critical to the very ability to "present a defense...[a] defendant's version of the facts".