Just put Robert Downey Jr. and Robert Duvall in a room together and you’ll have a movie, a truism that “The Judge” does its damnedest to disprove. David Dobkin’s film doesn’t leave a melodramatic stone unturned, adding to its courtroom drama a sentimental tsunami of story lines: a mother’s funeral, a father-son reckoning, a fight with cancer, a dash of alcoholism, a custody battle, a mentally challenged younger brother, and a hint of possible incest, to boot. Objection!