Actually, that is what Yates v. United States turned on and why after the Supreme Court said that distributing literature could not be sufficient but must be paired with actual concrete steps to make it happen there was only one further conviction under the Smith Act (for a Communist Party member who was also a martial arts instructor).
Read Yates v. United States. The conviction was reversed and it brought an end to Smith Act prosecutions of the Communist Party.
Yates also largely overruled Whitney v. California (and set up the formal overrule in Brandenburg). It is worth noting however that although the Supreme Court (this was decades before Yates) held that Communist Party membership itself could be subject to prosecution, Brandeis's concurrence apparently lead the governor of the state to pardon Whitney.
Read Yates v. United States. The conviction was reversed and it brought an end to Smith Act prosecutions of the Communist Party.
Decision at: http://www.law.cornell.edu/supct/html/historics/USSC_CR_0354...
Oral argument at: http://www.oyez.org/cases/1950-1959/1956/1956_6
Yates also largely overruled Whitney v. California (and set up the formal overrule in Brandenburg). It is worth noting however that although the Supreme Court (this was decades before Yates) held that Communist Party membership itself could be subject to prosecution, Brandeis's concurrence apparently lead the governor of the state to pardon Whitney.