The Classified Information Procedures Act or CIPA is codified as the third appendix to Title 18 of the U.S. Code, the title concerning crimes and criminal procedures. The U.S. Code citation is 18 U.S.C. App. III. Sections 1-16. From Wikipedia
Federal prosecutors cite national security in limiting evidence disclosure in the bribery case involving U.S. Representative Henry Cuellar and foreign entities.