WASHINGTON — As the Supreme Court on Monday tried to puzzle out what threats may be prosecuted as crimes, Chief Justice John G. Roberts Jr. cited an unlikely source: the rapper Eminem.
Treading gingerly, the chief justice quoted vivid lyrics from '97 Bonnie and Clyde in which Eminem seems to threaten to drown his wife.
"Could that be prosecuted?" Roberts asked Michael R. Dreeben, a government lawyer.
Dreeben said no and started to say something about context. Roberts interrupted.
"Because Eminem said it instead of somebody else?" he asked.
The case before the justices also involved threatening rap lyrics arising from domestic troubles. They were posted on Facebook by Anthony Elonis, a Pennsylvania man who had adopted the rap persona Tone Dougie. The posts, long tirades in the form of rap lyrics, were punctuated by brutally violent language, most of it directed against his estranged wife.
He wrote that he would like to see a Halloween costume that included his wife's "head on a stick." He talked about "making a name for myself" with a school shooting, saying, "Hell hath no fury like a crazy man in a kindergarten class." He fantasized about killing an FBI agent.
Some of the posts contained disclaimers or indications that they aspired to be art or therapy. At Elonis' trial, his estranged wife testified that she understood the posts as threats.
"I felt like I was being stalked," she said. "I felt extremely afraid for mine and my children's and my family's lives."
Elonis was convicted under a federal law that makes it a crime to communicate "any threat to injure the person of another." He was sentenced to 44 months.
John P. Elwood, a lawyer for Elonis, said his client's posts included elements of entertainment.
Justice Samuel A. Alito Jr. responded warily.
"This sounds like a road map for threatening a spouse and getting away with it," Alito said. "You put it in rhyme and you put some stuff about the Internet on it and you say, 'I'm an aspiring rap artist.' And so then you are free from prosecution."
The question for the justices in Monday's case was whether prosecutors had done enough to prove Elonis' intent. Dreeben, the government lawyer, said the words and their context were enough.
The standard proposed by the government, he said, would hold people accountable "for the ordinary and natural meaning of the words that they say in context."
The lower courts sided with Dreeben, the government lawyer. All the prosecution had to prove, the trial judge ruled, was that a "reasonable person" would foresee that others would view his statements "as a serious expression of an intention to inflict bodily injury or take the life of an individual."
The court could ground such a ruling in the First Amendment or in interpreting the federal law on threats, though the latter seemed more likely.
But some justices seemed nervous about placing too stringent a burden on prosecutors.
"How does one prove what's in somebody else's mind?" Justice Ruth Bader Ginsburg asked. "In this case, the standard was 'Would a reasonable person think that the words would put someone in fear?' and reasonable people can make that judgment. But how would the government prove whether this threat in the mind of the threatener was genuine?"
That echoed Dreeben, who insisted that the proper standard was an objective one that looked to what a reasonable person would have understood in the circumstances.
Roberts tried to refine the point.
"Is it a reasonable person?" he asked. "Or is it a reasonable teenager on the Internet?"
There was laughter, and then Dreeben responded. "If there is such a thing," he said.