Nate Parker’s “American Skin” opens with a traffic stop, captured on body cams. The driver, Lincoln (played by Parker), watches helplessly as his teenage son, Kijani (Tony Espinosa), is shot down by a police officer. The incident plants the seed for what becomes a kind of vigilante courtroom drama.

A year after the shooting, a student filmmaker, Jordin (Shane Paul McGhie), undertakes a documentary about Lincoln and his loss. He interviews Lincoln and chronicles the aftermath when Kijani’s killer goes free. Then Lincoln, a soft-spoken Marine veteran, takes Jordin and his small crew on a car ride that unexpectedly turns into a mission to kidnap a police captain.

Lincoln goes on to take an entire police station hostage at gunpoint, with help from friends, all filmed by Jordin’s team. He launches an ad hoc trial of the freed cop, Randall (Beau Knapp), appointing jurors from the jail’s orange-suited prisoners and others who happen to be present. The stage is set for the airing of grievances, prejudices and outrage. (The improvised court setting may feel fraught for another reason: Parker’s 2016 debut feature as director, “The Birth of a Nation,” foundered after new controversy surrounding rape charges he faced and was acquitted of in 2001.)

The screenplay’s ample chances for grandstanding don’t serve any actor well for long. The button-pushing dialogue during the trial sounds like agree-or-disagree statements from a poll of racial attitudes. Instead of lending immediacy, the padded-out documentary conceit only spotlights the stiltedness, and Parker falls short of building credible drama out of urgent issues.

American Skin
Rated R. Running time: 1 hour 29 minutes. Rent or buy on Apple TV, Google Play and other streaming platforms and pay TV operators.