I'm not going to engaged with someone on HN debating legal principles regarding something so straight forward. And, as I said, this is off the top of my head. It's basic constitutional law which I haven't found necessary to research. After that sentence I googled McCarthyism and found that SCOTUS ruled in multiple cases that Senator McCarthy and his supporters violated the First Amendment rights of the citizens they accused of communism. I haven't read the opinions, but I am confident they ( and many others ) support the very basic principles I speak of.