Christopher has written for television and films including "Casey Jones", "Joy Ride", "Wanted: Dead or Alive", "The Rebel", "Zane Grey Theater", "The Dick Powell Show", "Cimarron Strip", "Scott Joplin", "Escape from Bogen County", "The Choirboys", "Pope John Paul II", "Prison for Children" and "Equal Justice".

Christopher was president of the Writers Guild of America, West from 1965 to1967. He teaches advanced screenwriting to undergraduates in the Filmic Writing Program at the University of Southern California School of Cinema-Television.