Black speech has always been policed. Many Southern colonies and states outlawed literacy among slaves. Black speech during the century of Jim Crow was regulated by legal and extralegal means. The FBI monitored civil rights leaders’ speech, both public and private, and sought to “neutralize” leaders who spoke against the white order. Even in the present, President Obama has been seen to tightly manage his rhetoric on race. First Amendment notwithstanding, speech has never been free for black Americans.

A new threat to black speech is lurking in the dark recesses of the justice system, as rap lyrics are being admitted as evidence in trials “with alarming regularity,” say professors Erik Nielson and Charis Kubrin, who study the shockingly widespread, yet largely unknown juridical tactic. Nielsen, who began uncovering the judicial phenomenon in 2011, estimates the number of cases where lyrics are used in the hundreds. Nielson finds a historically familiar exception to Constitutional liberty: “Black speech is not always protected in the same way” as other speech, he says, and rap music is the only genre singled out as admissible evidence in court. In fact, “no other fictional form — musical, literary or cinematic — is used this way in the courts,” he points out in an op-ed penned with rapper Killer Mike for USA Today.

In August, New Jersey rapper Vonte Skinner narrowly avoided a 30-year sentence for attempted murder when that state’s supreme court finally overturned a 2008 conviction and ruled against the admission of Skinner’s violent lyrics. As Rap Genius contributors noted, Skinner’s evidentiary lyrics were no worse than those of platinum-selling hip hop superstars. To ascribe to one’s character and conduct the content of one’s art would place many of our most beloved artists under suspicion of unspeakable atrocities. From Dostoevsky’s Raskolnikov to Brian de Palma’s Scarface to Eminem’s Stan, the freedom of speech permits one to depict criminality and violence without being suspected of engaging in it. American society doesn’t function without that bedrock protection. But prosecutors know their juries. The specter of the thug so frightens, is so despised, that entire courtrooms in America don’t realize when they’ve careened full-speed into unconstitutionality.

With legal help from the ACLU and public exposure brought by Nielson and Kubrin, the Skinner case was pulled from its dark corner of the justice system, and the New Jersey Supreme Court would concur with an appellate court ruling, finding “significant doubt about whether the jurors would have found the defendant guilty if they had not been required to listen to the extended reading of these disturbing and highly prejudicial lyrics.”

But it’s one case among many hundreds, perhaps thousands, when lyrics presented during sentencing are included, estimates Nielson. The increasing freedom prosecutors feel in deploying rap lyrics as evidence has led to the case against San Diego rapper Brandon Duncan, who is charged not with active participation in a crime but with allegedly benefiting from and furthering the criminal activity of a gang with whom Duncan is allegedly affiliated. He is not accused of having any prior knowledge of the crime or being materially or organizationally involved. The nine counts leveled against Duncan could amount to a life sentence if he is maximally convicted.