Screenwriter Gregory Poirier (“Rosewood”) will adapt John Grisham’s “The Runaway Jury” for director Joel Schumacher. Poirier will work on the script as it heads for a start in October. Pic is from Warner Bros. and New Regency Prods. Grisham and T.R. Pearson wrote a first draft of the script, but as the pic heads into casting and a start date, the production needed a screenwriter based on the West Coast, Schumacher said. Poirier also wrote the script “Gossip,” which is set up at Schumacher’s Warner Bros.-based production company. ICM reps Poirier.