He wrote a rap song. It helped put him in prison for life.

I have been reporting on the use of rap lyrics in criminal investigations and trials for more than two years, building a database of cases like Mr. Canady’s in partnership with the University of Georgia and Type Investigations. We have found that over the past three decades, rap — in the form of lyrics, music videos and album images — has been introduced as evidence by prosecutors in hundreds of cases, from homicide to drug possession to gang charges. Rap songs are sometimes used to argue that defendants are guilty even when there’s little other evidence linking them to the crime. What these cases reveal is a serious if lesser-known problem in the courts: how the rules of evidence contribute to racial disparities in the criminal justice system…

Research has shown that rap is far more likely to be presented in court and interpreted literally than other genres of music. A 2016 study by criminologists at the University of California, Irvine, asked two groups of participants to read the same set of violent lyrics. One group was told the lyrics came from a country song, while the other was told they came from rap. Participants rated whether they found the lyrics offensive and whether they thought the lyrics were fictional or based on the writer’s experience. They judged the lyrics to be more offensive and true to life when told they were rap.

“The findings suggest,” the authors wrote, “that judges might underappreciate the extent to which the label of lyrics — and not the substantive lyrics themselves — impact jurors’ decisions.” Simply describing music as rap, they concluded, is enough to “induce negative evaluations.”