Letters and writings as nonmailable
Official text prohibited actmental stateif conditionpenaltylegal term
(a) Every letter, writing, circular, postal card, picture, print, engraving, photograph, newspaper, pamphlet, book, or other publication, matter or thing, in violation of sections 499, 506, 793, 794, 915, 954, 956, 957, 960, 964, 1017, 1542, 1543, 1544 or 2388 of this title or which contains any matter advocating or urging treason, insurrection, or forcible resistance to any law of the United States is nonmailable and shall not be conveyed in the mails or delivered from any post office or by any letter carrier.
(b) Whoever uses or to use the mails or Postal Service for the transmission of any matter declared by this section to be nonmailable, shall be or imprisoned not more than ten years or both.
History: (June 25, 1948, ch. 645, 62 Stat. 782 (PDF, 39 MB); Pub. L. 86–682, §12(b), Sept. 2, 1960, 74 Stat. 708 (PDF, 24 MB); Pub. L. 91–375, §6(j)(27), Aug. 12, 1970, 84 Stat. 780 (PDF, 12 MB); Pub. L. 101–647, title XXXV, §3552(a), Nov. 29, 1990, 104 Stat. 4926 (PDF, 27 MB); Pub. L. 103–322, title XXXIII, §330016(1)(K), Sept. 13, 1994, 108 Stat. 2147 (PDF, 52 MB).)
Simplified explanation
Some materials cannot be sent by mail, including items that violate certain listed federal laws (such as some forgery, spying, and passport laws) and material urging treason, rebellion, or violent resistance to U.S. law. It is a federal crime to use or try to use the mail to send these items.