Washington(CNN) Several famous rappers are urging the US Supreme Court to take up a case involving a Pittsburgh rapper and whether his song lyrics are protected under the First Amendment.

In a legal brief filed Wednesday, rappers Killer Mike, Chance the Rapper, Meek Mill, Yo Gotti, Fat Joe, and 21 Savage were among a group of artists and scholars who say Jamal Knox's rap song "F*** the Police" is a "political statement ... that no reasonable person familiar with rap music would have interpreted as a true threat of violence."

"A person unfamiliar with what today is the nation's most dominant musical genre or one who hears music through the auditory lens of older genres such as jazz, country, or symphony, may mistakenly interpret a rap song as a true threat of violence and may falsely conclude a rapper intended to convey a true threat of violence when he did not," they wrote.

Knox performs under the rap name "Mayhem Mal," and together with Rashee Beasley, who goes by "Souja Beaz," formed the rap group "Ghetto Superstar Committee." The two were arrested in 2012 during a routine traffic stop on gun and drug charges.

After their arrest, they wrote and recorded a song titled, "F*** the Police," seen as a homage to the N.W.A. 1988 rap song "F*** tha Police." Knox and Beasley's song, posted on Facebook and YouTube, included the names of the two Pittsburgh officers who arrested them with lyrics like, "I'ma jam this rusty knife all in his guts and chop his feet" and "Well your shift over at three and I'm gonna f*** up where you sleep."

The song ended, "Let's kill these cops cuz they don't do us no good."

The officers testified that the lyrics made them "nervous" and concerned for their safety, with one saying it led him to leave the police force.

Knox was found guilty and sent to prison for two years on charges of "terroristic threats and witness intimidation" stemming from the song, and the separate gun and drug charges.

At his sentencing, Knox said he did not intend any harm against the officers and that he should be viewed separately from his rap persona.

Knox appealed his conviction with the Pennsylvania state Supreme Court, which upheld the ruling last year.

"...The rap song here is of a different nature and quality," the court's chief justice wrote in the majority opinion.

"They do not include political, social, or academic commentary, nor are they facially satirical or ironic. Rather, they primarily portray violence toward the police," the opinion read.

The rappers, in their brief filed Wednesday, said that the opinion "reveals a court deeply unaware of popular music generally and rap music specifically."

The song, they said, represented the "perspective of two invented characters in the style of rap music, which is (in)famous for its exaggerated, sometimes violent rhetoric, and which uses language in a variety of complex ways."

"It is not intended to be taken literally, something that a reasonable listener with even a casual knowledge of rap would understand," they wrote, also providing a "primer" to the justices on hip hop and rap music.

Knox's case would test the legal standard for whether a statement is a "true threat" and unprotected by the First Amendment.

The question, as it is presented by Knox's lawyers, is whether a government must show that a "reasonable person" would regard someone's statement as a sincere threat of violence, or whether it is enough to show only that the speaker's subjective intent was to threaten.

The Pennsylvania court was divided over the standard for what determines a statement to be a "true threat."

"A majority of courts have held that the standard is objective and requires a showing that a 'reasonable person' would regard the statement as a sincere threat of violence," Knox's lawyers wrote in their petition urging the justices to take the case. "But other courts have held that the standard is subjective and assess only whether the speaker intended to communicate such a threat."

The split has led to uncertainty over the limit of the First Amendment's protection of free speech, which the Supreme Court would have the opportunity to clear up if it takes the case.

If the Supreme Court decides to take up Knox's case, it would likely not be heard until the session that begins next October.

CORRECTION: The year in which N.W.A.'s "F*** the Police* was released has been corrected.