1 U.S.C. § 212

In addition the Superintendent of Documents shall, at the beginning of the first session of each Congress, supply to each Senator and Representative in such Congress, who may in writing apply for the same, one copy each of the Code of Laws of the United States, the Code of Laws relating to the District of Columbia, and the latest supplement to each code: Provided , That such applicant shall certify in his written application for the same that the volume or volumes for which he applies is intended for his personal use exclusively: And provided further , That no Senator or Representative during his term of service shall receive under this section more than one copy each of the volumes enumerated herein.