The premise of “Jury Duty” — placing a non-actor in the middle of an entirely staged trial — could have easily led the show to mean-spirited-prank territory. Instead, the cast manages to land laughs while making the person who thinks it’s all real, Ronald Gladden, into a hero. For James Marsden, who plays a Hollywood jerk version of himself on the show, that was the most important thing. “I’ll make an ass of myself and have fun doing it, but I never want him to be the butt of the joke,” he shares.In this episode of “The Envelope” podcast, Marsden discusses how the cast and crew managed to pull it all off, why the role interested him, and how — despite his very believable performance on ”Jury Duty” — he strives to keep his ego from ruining his reputation in real life. To read a full transcript of this interview, please visit the episode page at latimes.com.