In bringing criminal charges against an Internet radio host and blogger who wrote that three judges "deserve to be killed" for their ruling in a 2nd Amendment case, the U.S. Justice Department isn't risking much public criticism. But the prosecution of the despicable Hal Turner looks like an attempt to punish speech, not action.
Turner long has ranted against public officials and others who don't share his right-wing views; his rhetoric is so vile and his manner so confrontational that they border on incitement of violence. But under the 1st Amendment, "bordering on incitement" isn't enough to justify punishment. In 1969, the court overturned the conviction of a Ku Klux Klan leader who had urged "revengeance" against the government for suppressing the white race. The court ruled that advocating the use of force couldn't be punished "except where such advocacy is directed to inciting or producing imminent lawless action and is likely to incite or produce such action."
Why should the 1st Amendment protect someone who publicly says that a politician or judge or doctor should be killed? Two reasons: Such statements are often hyperbole, and even statements that include an endorsement of violence can serve the purpose of communicating outrage about public policies.