18 U.S.C. § 504 : US Code - Section 504: Printing and filming of United States and foreign obligations and securities

      Notwithstanding any other provision of this chapter, the
    following are permitted:
        (1) The printing, publishing, or importation, or the making or
      importation of the necessary plates for such printing or
      publishing, of illustrations of - 
          (A) postage stamps of the United States,
          (B) revenue stamps of the United States,
          (C) any other obligation or other security of the United
        States, and
          (D) postage stamps, revenue stamps, notes, bonds, and any
        other obligation or other security of any foreign government,
        bank, or corporation.

      Illustrations permitted by the foregoing provisions of this
      section shall be made in accordance with the following conditions
      - 
        (i) all illustrations shall be in black and white, except that
      illustrations of postage stamps issued by the United States or by
      any foreign government and stamps issued under the Migratory Bird
      Hunting Stamp Act of 1934 may be in color;
        (ii) all illustrations (including illustrations of uncanceled
      postage stamps in color and illustrations of stamps issued under
      the Migratory Bird Hunting Stamp Act of 1934 in color) shall be
      of a size less than three-fourths or more than one and one-half,
      in linear dimension, of each part of any matter so illustrated
      which is covered by subparagraph (A), (B), (C), or (D) of this
      paragraph, except that black and white illustrations of postage
      and revenue stamps issued by the United States or by any foreign
      government and colored illustrations of canceled postage stamps
      issued by the United States may be in the exact linear dimension
      in which the stamps were issued; and
        (iii) the negatives and plates used in making the illustrations
      shall be destroyed after their final use in accordance with this
      section.

      The Secretary of the Treasury shall prescribe regulations to
      permit color illustrations of such currency of the United States
      as the Secretary determines may be appropriate for such purposes.
        (2) The provisions of this section shall not permit the
      reproduction of illustrations of obligations or other securities,
      by or through electronic methods used for the acquisition,
      recording, retrieval, transmission, or reproduction of any
      obligation or other security, unless such use is authorized by
      the Secretary of the Treasury. The Secretary shall establish a
      system to ensure that the legitimate use of such electronic
      methods and retention of such reproductions by businesses,
      hobbyists, press or others shall not be unduly restricted.
        (3) The making or importation of motion-picture films,
      microfilms, or slides, for projection upon a screen or for use in
      telecasting, of postage and revenue stamps and other obligations
      and securities of the United States, and postage and revenue
      stamps, notes, bonds, and other obligations or securities of any
      foreign government, bank, or corporation. No prints or other
      reproductions shall be made from such films or slides, except for
      the purposes of paragraph (1), without the permission of the
      Secretary of the Treasury.

      For the purposes of this section the term "postage stamp"
    includes postage meter stamps.