Black people are overrepresented within the criminal-justice system, and race relations in America will never truly budge until “equality under the law” is more than a quaint phrase. But equality is, of course, impossible if the black people grappling with courts and imprisonment are routinely misunderstood.

Transcription mistakes can happen quite innocently. As far back as the 1930s, white men and women tasked with transcribing recordings of ex-slaves produced error-ridden manuscripts. One man was supposed to have said that after Emancipation Day, “the colored people sure went for!,” which sounds odd grammatically and substantively; why wouldn’t ex-slaves have been “for” their freedom? It turned out that the man was saying that ex-slaves “sure been poor,” a straightforward statement.

I thought of this recently when I was staying at a hotel and asked a black woman working at the front desk where I could get a cup of coffee. When she pointed toward the restaurant, I said it was closed. Then she pointed more directly to a table with coffee urns near the restaurant—I was sleepy and hadn’t seen it—and she said, with warm irony, “Dat table, dey close?” Her utterance could easily have thrown a foreigner, given that in Black English you can leave out the are of Are they closed? and the final -d of closed. Even some native English speakers may have misheard her without a certain amount of familiarity with the dialect.

Read: What does it mean to “sound” black?

When someone in a position of authority draws attention to the differences between standard and Black English, the response is often perplexity and derision. That was true in 2010 when the Drug Enforcement Administration put out a call for Black English translators so the agency could better understand conversations on wiretaps. Some in the media, poking fun at the whole project, suggested that Black English is simply a collection of slang words or even just a sloppy way of enunciating. The pervasive assumption was that black speech differs from mainstream speech only in some spicy lingo plus various instances of “broken” grammar.

In fact, Black English is not deficient but alternate. There is no scientific basis for judging Black English grammatical structures as faulty or unclear, and a Martian assigned to learn English who happened to land on the South Side of Chicago rather than in Scarsdale, New York, would have the same challenge in mastering the rules and nuances of the local speech. For example, the come in “He come tell ’bout I’m gonna take the TV” is used to convey indignation, and has inspired a linguistics article itself. Miss this and the man’s whole meaning is lost—and to his possible detriment.

Even those who accept that Black English is more than slang may feel that a translation approach is unwarranted, condescending, or both. Sometimes it may be. In 1996, the Oakland, California, school district proposed to use Black English in the classroom as a sort of training wheel. The idea was that kids raised with Black English as a home language had trouble learning to read because standard English was so unfamiliar. But many (including me) thought that was a misdiagnosis: Black people, including kids, use Black English alongside standard English rather than exclusively.