Congress passed the Smith Act in 1940 -- making it unlawful to advocate the violent overthrow of the U.S. government.
The Smith Act of 1940 5 made it a criminal offense for anyone to knowingly or willfully advocate, abet, advise, or teach the duty, necessity, desirability, or propriety of overthrowing the Government of the United States or of any State by force or violence, or for anyone to organize any association which teaches, advises, or encourages such an overthrow, or for anyone to become a member of or to affiliate with any such association.
Ch. 439, 54 Stat. 670, 18 U.S.C. Sec. 2385.
TITLE 18 - CRIMES AND CRIMINAL PROCEDURE
PART I - CRIMES
CHAPTER 115 - TREASON, SEDITION, AND SUBVERSIVE ACTIVITIES
-HEAD-
Sec. 2385. Advocating overthrow of Government
-STATUTE-
Whoever knowingly or willfully advocates, abets, advises, or
teaches the duty, necessity, desirability, or propriety of
overthrowing or destroying the government of the United States or
the government of any State, Territory, District or Possession
thereof, or the government of any political subdivision therein, by
force or violence, or by the assassination of any officer of any
such government; or
Whoever, with intent to cause the overthrow or destruction of any
such government, prints, publishes, edits, issues, circulates,
sells, distributes, or publicly displays any written or printed
matter advocating, advising, or teaching the duty, necessity,
desirability, or propriety of overthrowing or destroying any
government in the United States by force or violence, or attempts
to do so; or
Whoever organizes or helps or attempts to organize any society,
group, or assembly of persons who teach, advocate, or encourage the
overthrow or destruction of any such government by force or
violence; or becomes or is a member of, or affiliates with, any
such society, group, or assembly of persons, knowing the purposes
thereof -
Shall be fined under this title or imprisoned not more than
twenty years, or both, and shall be ineligible for employment by
the United States or any department or agency thereof, for the five
years next following his conviction.
If two or more persons conspire to commit any offense named in
this section, each shall be fined under this title or imprisoned
not more than twenty years, or both, and shall be ineligible for
employment by the United States or any department or agency
thereof, for the five years next following his conviction.
As used in this section, the terms ''organizes'' and
''organize'', with respect to any society, group, or assembly of
persons, include the recruiting of new members, the forming of new
units, and the regrouping or expansion of existing clubs, classes,
and other units of such society, group, or assembly of persons.