whats the movie with a black protaganist in a world with london robot cops

In the future, America is a dystopian wasteland. The latest scourge is Ma-Ma, a prostitute-turned-drug pusher with a dangerous new drug and aims to take over the city. The only possibility of stopping her is an elite group of urban police called Judges, who combine the duties of judge, jury and executioner to deliver a brutal brand of swift justice. But even the top-ranking Judge, Dredd, discovers that taking down Ma-Ma isn’t as easy as it seems in this explosive adaptation of the hugely popular comic series.

A struggling black actor's pursuit of a role spirals into a psychological descent, blurring the lines between his identity and the villain he portrays.