By Alan Zilberma, Special To The Washington Post In the fact-based drama “Marshall” — a throwback to such courtroom-focused procedurals as “Witness for the Prosecution” and “To Kill a Mockingbird” — Thurgood Marshall is seen as something of a legal superhero. The late Supreme Court justice cuts a striking figure as he prepares to don his judicial robes before the film flashes back to the early 1940s, when, as a young attorney for the NAACP, he brought to the job an unwavering commitment to justice (and a willingness to get into bar brawls). This oversimplified rendering, however, is complicated by the fact that the film is set in the Jim Crow era and centers on the case of a black man who has been accused of raping a white woman.