American 'Free' Speech

As a follow-up on Anders' posting Mixed reactions on my "niggardly"-posting I wanted to look more into the concept of free speech.

How can a person be fired on grounds of teaching kids a perfectly sound work, listed in any dictionary? Wouldn't this infringe on that teacher's rights?

Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the government for a redress of grievances.

- U.S. Constitution, 1st amendment

So, now, if I get it right it shouldn't be possible to make any laws that abridging the freedom of speech. I guess you don't need a law to fire someone, but for labour court to uphold the discharge I would presume that some law is necessary.

Naturally all comes down to interpretation. Or then again, maybe there is no such thing as free speech anymore. Maybe it is free-speech-if-you-make-sure-noone-feeling-bad-about-it. I believe that the term for it is fair speech.

In Capitalism and Freedom, Milton Friedman discusses the soundness of a general freedom of speech. Why not enact a law affirming or denying to each the right to spread his particular views? I believe the reason is clear. What is the chance of anyone advocating, say, racism would be allowed to do so? Probably and such proposal would be rejected by a wast majority.

Now lets bundle all these proposals, everything from people advocating good weather to those advocating racism. [...] to vote whether free speech should be denied in all cases or permitted all in alike. My bet would be that it would be accepted with a vast majority!

Freeman's belief is that most people are more afraid of being deprived of their rights, becoming a minority than they really care about depriving minorities they are not a part of of theirs. I agree with the analysis, and I would go as far as calling it a 'free-speech-when-it-suits-me' system. But I will have to admit that the fine line between harassment and freedon is hard to draw...

In my opinion it is dangerous, really dangerous for any society to become so pedantic that one might get fired upon using a word that only proves that one has a rich language.

Where did common sense go?