Freedom of speech is understood to be fundamental in a democracy. What limitations to freedom of speech are there in the United States of America and in Canada? Is Holocaust denial an example?
Up front: Holocaust Denial is not limited under U.S. law.
There is an adequate list on Wikipedia of free speech exceptions, that for convenience I will replicate here:
- Communicative impact restrictions (e.g. incitement, elicitation)
- False statements of fact (e.g. libel, slander, perjury)
- Obscenity (very tightly interpreted, and only regulated in public)
- Child pornography
- Fighting words and offensive speech (closely related to incitement)
- Speech owned by others (i.e. copyright violations)
- Commercial speech (i.e. advertisement restrictions)
In general, free speech is highly protected in the U.S., and perhaps has greater protections than any other right, under the law. In order to restrict free speech under U.S. law, one must show that the speech itself causes immediate physical or monetary harm (e.g. child pornography, libel, false advertisement) or that it is likely to result in actions which will cause immediate physical or monetary harm (e.g. "lets go lynch that ^!@@$%!")
Worthy of note within discussions of free speech in the U.S. is the ongoing debate about "speech codes," which are shockingly common on U.S. campuses given how unpopular they are across the political spectrum. Some argue that speech that is emotionally damaging is sufficient harmful as to warrant restriction. Opponents have countered that the purposes of the university is to challenge existing ideas and that sometimes is uncomfortable. Importantly, none of this is a constitutional issue, except in state run universities, because private institutions can restrict speech if they want. Furthermore, it seems as though the impetus to restrict speech, even in this very narrow area, is waning although the situation could change.
In the United States, free speech is everything except when there is an illicit action associated with it.
One poster mentioned child pornography. That is not an exception to free speech. The prohibition is on using children in such pornography. If you want to do lifelike computer animations of children engaging in unnatural acts, knock yourself out, pervert. It's perfectly legal.
That is, unless you misrepresent it as having actual children in it to induce people to buy your smut. This is the same as any commercial misrepresentation designed to induce a purchase based upon false information.
Libel/slander is not an exception to free speech. You can say whatever you want about someone. However, if it is false, you have to compensate that person for their injury. There is no criminal penalty for libel/slander in the U.S.
You are free to say "There is a fire in the the theater" when you are at home. You can't say the same when you are in the theater when it will induce panic. If your at a church dinner and say "That Schmitty pisses me off, someone should shoot him" you're engaging in free speech. If you make that same statement at a gathering of hit men to induce them to take an action, your speech is still free but your inducement to kill is still punishable.
In other words, you are free to speak but your speech may have consequences that you are libel for in some limited circumstances.
IMHO, the Wikipedia article on Free Speech Exceptions is a very poor analysis of the law.