How did things like the smith act and the huac limit american rights and freedoms during the cold war?

So, it was passed during the war, and it made it an offense to advocate the violent overthrow of government. Not only were you not able to advocate the violent overthrow of government, you also could not belong to a group that advocated the violent overthrow of the government. Why was that bad? Because it was later used to prosecute members of the Communist and Socialist Workers parties