Erik Nielson is an assistant professor of liberal arts at the University of Richmond.

How well should a “reasonable” person understand rap music?

Last week, the Supreme Court was faced with precisely that question when it heard arguments in Elonis v. U.S. , a case with major implications for the kinds of speech that will — and will not — be protected in the age of social media.

The case dates to 2010, when 27-year-old Anthony Douglas Elonis was charged with making unlawful threats after posting violent Facebook messages about his estranged wife and, once law enforcement got involved, an FBI agent. The messages often appeared in the form of rap lyrics, and Elonis frequently signaled that they were forms of creative expression: He adopted the name “Tone Dougie” as a Facebook alter ego, described his posts as “fictitious lyrics” and included statements such as “art is about pushing limits.” As John P. Elwood, Elonis’s lawyer, pointed out during oral argument before the Supreme Court: “This is the only threats case I can think of where somebody is saying, this isn’t a threat, this isn’t a threat, this isn’t a threat.”

Nevertheless, despite his insistence at trial that he was merely borrowing from the familiar conventions of rap music, Elonis was found guilty and sentenced to nearly four years in prison.

Now the justices stand tasked with determining whether speech like Elonis’s rises to the level of a “true threat.” Lower courts have been applying very different standards. Most, including the U.S. Court of Appeals for the 3rd Circuit — which heard, and denied, Elonis’s appeal — consider whether a “reasonable person” would interpret something as a threat, essentially ignoring a speaker’s intentions. But other courts insist that the speaker’s intent must be considered. When they rule on Elonis, the justices will provide some much-needed guidance to the judiciary.

Their decision will have ramifications for everyone who uses social media, but nowhere will the consequences be felt more acutely than among artists who disseminate rap music. Over the past decade, we’ve seen a precipitous increase in the use of rap lyrics and videos as evidence in criminal trials. In hundreds of cases across the country, prosecutors seeking easy convictions have effectively denied rap the status of art — ignoring its use of figurative language, exaggeration and complex manipulation of identity — and presented the lyrics to juries as autobiographical confession rhymed over a beat.

No other fictional genre is used this way in courts, and the results can be devastating for the young men of color who make up the vast majority of defendants in such cases. As University of Georgia law professor Andrea Dennis wrote, prosecutors who are permitted to use rap as evidence “obtain a stranglehold on the case.” That’s because juries that are unaware of the conventions of rap music, particularly the violent “gangsta” subgenre, can easily be persuaded to conflate a defendant with the fictional persona in his songs.

In most situations, prosecutors introduce lyrics to suggest a defendant’s involvement in some underlying crime, but Elonis represents a new wave of cases in which the lyrics themselves are the crime. I have served as a defense consultant on several of these cases, most of which involved lyrics that were posted to popular sites such as YouTube or Facebook and later discovered by authorities.

This presents a real dilemma for aspiring rappers. Social media are a vital tool for distribution, especially for up-and-coming artists without the support of a record label. At the same time, they have become a gold mine for law enforcement, with police across the country spending a surprising amount of time monitoring sites for information, including rap songs, that could lead to a criminal charge. The head of the gang unit in Newport News, Va. — the site of a recent, high-profile case involving a rap video posted to YouTube — revealed that his officers now spend about half their time in front of a computer where they monitor social media sites.

Like rap or hate it, this is a concerning development. As my colleague Charis E. Kubrin and I argued in an amicus brief filed to the Supreme Court on behalf of Elonis, the young men and women who are writing and producing rap songs, even those with violent content, are frequently doing so to escape a life of crime, not to perpetuate one. Like screenwriters of gangster films or authors of horror novels, they are creating a form of fictional entertainment. But it can be one they hope provides a path away from the very kind of life they are portraying.

Surely reasonable people can understand that. And yet many don’t, and young artists are paying a steep price as a result. During oral argument last week, Chief Justice John Roberts got it right when he noted that the government’s position — that a speaker’s intent is not necessary to determine what amounts to a threat — “does subject to prosecution the lyrics that a lot of rap artists use.”

So when the justices rule on Elonis , they won’t simply be settling a question of true threats jurisprudence. They will be deciding whether, in a country rooted in a commitment to free speech, it’s reasonable to throw people in prison for their art.