36 CFR § 1254.40 - How does NARA prevent removal of documents?
(a) You must not remove documents from a research room. Removing, mutilating, or revising or otherwise altering documents is forbidden by law and is punishable by fine or imprisonment or both (18 U.S.C. 2071).
(b) Upon leaving the research room or facility, you must present for examination any article that could contain documents or microfilm, as well as presenting copies or notes to ensure that no original records are mixed in with them.
(c) To ensure that no one unlawfully removes or mutilates documents, NARA may post at the entrance to research rooms instructions supplementing the rules in this part. These instructions are specific to the kinds of records you use or to the facility where the records are stored.