“Mercy” follows Los Angeles detective Chris Raven (a perfectly generic Chris Pratt) after he awakens in the Mercy Court, accused of the murder of his wife. The Mercy Court was established, a helpful exposition dump reveals, after a wave of violence in a near-future, dystopian Los Angeles led to soaring crime rates. Mercy Court is led by an AI judge, Maddox (Rebecca Ferguson), who gives defendants a conveniently movie-length 90 minutes to prove their innocence or face execution. As the movie’s opening sequence says without a hint of irony, Mercy Court acts as “judge, jury and executioner” and defendants are “guilty until proven innocent.” Throughout the movie, Maddox offers additional, boring exposition of her role and the setting. “Mercy” is the newest directorial effort from Timur Bekmambetov, the pioneer of “screen-life” filmmaking, which sets a movie on a computer screen.