31 U.S.C. § 5155
Providing engraved plates of portraits of deceased members of Congress
On conditions the Secretary of the Treasury decides, the Secretary may send an engraved plate of a portrait of a deceased Senator or Representative to an heir or legal representative of such a Senator or Representative.
( Pub. L. 97–258 , Sept. 13, 1982 , 96 Stat. 993 .)