28 U.S. Code § 2247 - Documentary evidence
On application for a writ of habeas corpus documentary evidence, transcripts of proceedings upon arraignment, plea and sentence and a transcript of the oral testimony introduced on any previous similar application by or in behalf of the same petitioner, shall be admissible in evidence.
Derived from H.R. 4232, Seventy-ninth Congress, first session. It is declaratory of existing law and practice.