2 U.S. Code § 1944
2 U.S. Code § 1944 is about Wearing uniform on duty. It is under Part C (Uniform and Arms) of Subchapter I (Organization and Administration) of Chapter 29 (Capitol Police) of Title 2 (The Congress) of the Code.
The officers, privates, and watchmen of the Capitol police shall, when on duty, wear the regulation uniform.