The hallmark example of free speech in this country is the right of Nazis to march in a parade.  Unpopular speech is the most important speech to be protected.  Limits to using words are appropriate only when they rise to the level of an act that the speaker/writer  knows (and I don't know the exact legal standard to date) is likely to cause immediate physical harm or distress to another person.  Thus, "fire" is an act of incitement.  Libel/slander are acts that will cause immediate harm to reputation.  At a certain point repeated speech rises to level of harassment, and that is where so-called "bullying" (an emotional term) comes in.  It's harassment, which really isn't speech at all; it's an act.