Free Speech and Free Action
Freedom of speech differs from freedom of action. But speech and action are so closely interwoven in human behavior that it's not always immediately obvious which is which. Thus it's not surprising that we often criminalize speech as well as, or even instead of, the action that it accompanies. This is a mistake. Consider, for example, the apocryphal "snuff" movie. (I say apocryphal because, in my years of anti-censorship activism, I've encountered no credible evidence that such things actually exist. I believe that they're as much a myth as "Satanic ritual abuse.") A "snuff" movie, by definition, would entail murder. Therefore, anyone who made a "snuff" movie should be prosecuted for first-degree homicide.
You can not decriminalize an act by adding a speech element to it. Sexually coercing a child, for example, is a crime. Photographing the act does not make it less of a crime. The child-pornography analogy, of course, is misleading. When most people imagine child pornography they visualize pictures of children being raped. According to Congress, the Justice Department, and the Courts, however, any picture of any person under 18, clothed or unclothed, can be prosecuted as child pornography if the government decides to harass you. The legal definition is so broad (and it will become even broader) that people are prosecuted under child pornography laws for possessing material even when no laws whatsoever were violated in producing it. In other words, a legal activity can now become criminalized merely by adding a speech element to it. A now common example is the case of parents who are arrested for taking non-sexual but nude photographs of their own children.
Linked speech and action are not always concurrent. Consider, for example, conspiracies, bribes, or threats. (I'm talking about true conspiracies, bribes, or threats. I'm not talking about a parent who says, "Stop making that racket or I'm going to wring your neck.") In these cases, the criminal act occurs later in time than the associated speech. Sometimes, speech is a direct and immediate incitement to action. As Alan Dershowitz points out in his 1989 Atlanta Monthly essay "Shouting Fire!":
The message `Fire!' is directed not to the mind and conscience of the listener but, rather, to his adrenaline and his feet. It is a stimulus to immediate action..the shout of "Fire!" is not even speech, in any meaningful sense of that term. It is a clang sound, the equivalent of setting off a nonverbal alarm. Had Justice Holmes been more honest about his example, he would have said that freedom of speech does not protect a kid who pulls a fire alarm in the absence of a fire.
Inciting a frenzied mob to rioting or lynching is somewhat analogous. The Supreme Court, to its credit, recognized in 1969 in Brandenburg v. Ohio that speech advocating violence is protected unless the speech is "directed to inciting or producing imminent lawless action and is likely to incite or produce such action."
Limiting freedom of action is clearly not an exception to the First Amendment. Endless debate is possible, of course, over what constitutes speech. Some conservatives, for example, believe that images have no First Amendment protection. I personally believe that individual freedom should be maximized and that speech must be interpreted as broadly as possible.