A basic argument for protection of the right to free expression is that restrictions on what we are allowed to say or write would constitute an onerous intrusion in our personal lives. This, in itself, might be considered adequate justification for a strong interpretation of the First Amendment. But there is an even more powerful argument.
In the absence of infallible people, we have no really effective way of approaching truth or, alternatively, recognizing error, in any area of human activity, other than by exposing our ideas to the criticism of others, and carefully considering those criticisms. This process is fundamental to progress in science, and in every other area of human activity, including social and political matters. For this reason, freedom of expression is an essential component of democracy. The classic defense of free expression is the first two sections of John Stuart Mill's lucid, indispensable, essay, "On Liberty" [Mill].
Attacks on freedom of expression come from several very different directions. One major group of assailants comprises those seeking to establish, or maintain, dictatorial control of their countries. Obvious examples were Nazis, and Fascists, and the rulers of Czarist and Communist Russia. Myanmar (Burma), Kazakhstan, and Saudi Arabia are contemporary instances of countries currently regarded as being far from democratic, and where is little pretense that free speech exists.
There are also political leaders and government officials in countries, such as the US, purporting to be democracies, who seek to suppress free speech in order to conceal corrupt practices, and other embarrassing behavior. A common technique employed for this purpose is to invoke "national security" considerations as a pretext for suppressing the free flow of information [unger].
Others uncomfortable with free expression are people who are deeply offended by public criticisms of their religious beliefs. Still others, perhaps the largest group, fear that expression of bigoted notions about members of various groups would hurt their feelings, and might promote hostility toward them.
In recent years, Western European democracies, and Canada, have enacted legislation banning "hate speech" [Liptak][Greenwald]. This is defined typically as, "publicly making statements by which a group is threatened, insulted or degraded due to race, skin color, national or ethnic origin, faith or sexual orientation." (This is the Danish version.) Truth is not an acceptable defense.
The law was invoked not long ago in Denmark to convict Jesper Langballe, a right-wing member of the Folketing (parliament), who, in a newspaper column, made statements about honor killings and other abuses of Muslim women. He was fined about $1000 (the maximum sentence under the law is 2 years imprisonment.) In France, actress Brigitte Bardot, an animal rights activist, was fined $23,000, for criticizing a Muslim ceremony involving the slaughter of sheep [Maines]. (Almost all the European hate crime cases I have found involve Muslim targets.)
More generally, the European Court of Human Rights recently ruled that free speech protection does not extend to "concrete words constituting hate speech that might be offensive to individuals or groups." [Lopas]
Free expression advocates believe that outlawing hate speech, in addition to opening the door to widespread censorship, it is not an effective way to respond to bigotry [Mchangama]. A principal effect would likely be to allow bigots to play the role of heroes persecuted by a dictatorial government. The appropriate response to a nasty, or false, statement is a valid rebuttal. Where such rants have been widely disseminated, and might have significant effects, appropriate organizations can mount educational campaigns to counter them.
Laws against holocaust denial are of a similar nature. About 17 nations have such laws. These include Austria, Belgium, Canada,, France, Germany, Hungary, and Switzerland, but not the UK or any of the Nordic countries. As an example, David Irving, a right wing British author of histor