Elonis argued that, under the First Amendment, the government had to prove that he had a “subjective” intent to threaten. He said he lacked that, in part because some of his posts echoed words by rapper Eminem. The court of appeals held instead that the statute only requires that “a reasonable person would foresee that the statement would be interpreted by those to whom the maker communicates the statement as a serious expression of an intention to inflict bodily harm.”

Let’s break that down carefully. Elonis argues that the government must prove beyond a reasonable doubt that he was actually thinking, This message will terrify the person it refers too, and I want that. The government says that it must only prove that “a reasonable person” would have thought it would terrify.

There’s a split in the circuits over this issue. The Supreme Court took the case in order to clarify what the government needs to prove. If the standard is “reasonable person,” then the government can largely rely on the words a defendant uses and the general context in which they are used (for example, if they are sent directly to the target or confided to a blog, etc.). If it is “subjective intent,” however, prosecutors must use a defendant’s specific acts and circumstances to convince a jury he meant to alarm or threaten the targets.

Even if Elonis wins at the high court, he can still be prosecuted and possibly convicted under the “subjective” standard. It wouldn’t make convictions impossible—juries assess “subjective intent” all the time without needing telepathy—but it would make them harder to get.

But many people don’t understand the first step: What is a threat and why is it not protected by the First Amendment?

Federal courts summarize this area by saying that “true threats” are a historic exception to “the freedom of speech” protected by the First Amendment. “True” is an unfortunate term, because it convinces some people that the implied statement—“I am going to harm or kill you”—must be true.

But that’s wrong. Threats are not illegal because they signal an impending crime. Threats themselves are the crime. As the Supreme Court explained in the 2003 “cross-burning” case, Virginia v. Black:

The speaker need not actually intend to carry out the threat. Rather, a prohibition on true threats “protect[s] individuals from the fear of violence” and “from the disruption that fear engenders,” in addition to protecting people “from the possibility that the threatened violence will occur.”

To understand why this is true, imagine the delinquent high-school kids who declare a holiday by phoning a bomb threat to the school. There is no bomb, and the kids wouldn’t set one off if they could. Nevertheless, school must be canceled. The building has to be evacuated. The bomb squad must don protective gear and sweep the classrooms. Students will suffer nightmares. And authorities may someday be tempted to ignore notice of a genuine planned bombing. The threat itself is the harm.