Previous posts in this discussion:
PostVoorhis Act, 1940 (Luciano Dondero, Italy, 04/03/14 5:10 am)
In connection with JE's question about US repressive legislation, a relevant one is the Voorhis Act of 1940, which explicitly forbids international affiliation for political parties. That's why US Trotskyist parties usually avoid the typical Trotskyist formula (eg. "Italian section of the Fourth International") and formally are independent parties. This is occasionally used to justify political "deviations" from the line adopted elsewhere (Brussels, Paris, London...).
I suppose the aim of the Voorhis Act was not to make trouble for the Trots, but rather for the CP. I don't know if it was ever tested in court.
JE comments: With war on the horizon, 1940 was a productive year in the US for clamping down on radical politics. Representative Jerry Voorhis, a California Democrat and New Dealer, is probably best known for his 1946 re-election defeat by Richard Nixon. He certainly was far more handsome than RN; see for yourself: