California voters passed the Street Terrorism and Prevention Act, or STEP Act, by ballot initiative in 1988. The STEP Act provides criminal penalties against anyone who “willfully promotes, furthers, assists or benefits from any felonious conduct” by gang members. What voters likely did not realize in passing the law is that it might be used to sweep anyone who had any ties to a gang—sometimes, ties so tenuous that defendants wouldn’t know they had them—behind bars.

Since the law’s enactment, more than two dozen cases have been brought alleging “gang conspiracy” as the act defines the term. In many of these, such as 2013’s People v. Johnson, the charges also include actual violence. Duncan’s case is the first in which prosecutors have alleged that the rap lyrics and a couple of Facebook photos alone are sufficient to connect a defendant to a “gang conspiracy.”

Duncan has never been convicted of any crime. According to police records, he was a member of the Lincoln Park Bloods when he was a teenager in 1997, but Duncan’s beefs with rivals most often took the form of rap battles. He was arrested together with two Bloods members in 2008 on pimping charges, but the charges were dismissed. Duncan says he since given up any gang “fam” for a real one: his seven young kids and his girlfriend.

Duncan grew up in one of the most violent San Diego projects. Of his music, he says, “It’s entertainment. It’s not real.” Duncan has compared himself to Rick Ross, a former corrections officer turned rapper, explaining that his own raps are just telling the stories of urban communities. In “Fly Away,” he raps about his volatile beginnings and his struggle for a better life: “One day it's the sunshine, next day the rain came, but deep down inside you just playing the blame game.” Other lyrics criticize the gang life, as in “Wicked City,” where he asks, “Crime pays? What the fuck you talking ’bout?”

The bizarre case of Brandon Duncan illustrates what’s at stake in Elonis v. United States, a pending First Amendment case argued before the Supreme Court in December. Elonis raises the question of when words—in Elonis’ case, a series of Facebook posts—become criminal. The justices’ issue is a technical one: crafting the proper standard for determining whether a communicated expression is a “true threat.” Should it be enough to prove that a “reasonable person” would have known the words sounded like a threat, or should the government have to prove beyond a reasonable doubt that this defendant intended them to be a threat? Lurking behind that issue is the question of who judges the words of marginal figures like Tiny Doo.

Unlike Tiny, Anthony Elonis is not a recording rapper; but after his wife left him, he began posting “rap lyrics” on a Facebook page. They seemed to be threatening to harm his co-workers, his ex-wife, FBI agents, and children at nearby schools. The judge in the trial instructed the jury to evaluate Elonis’s lyrics by the “reasonable person” standard. He was convicted on four counts of making threatening communications and sentenced to three and a half years in prison.