Tom Selleck has had a long and successful career playing law heroes, including his roles as Frank Reagan on "Blue Bloods" and Thomas Magnum in the earlier CBS hit "Magnum PI." Despite the differences between these two shows, Selleck was attracted to them both because they were character-driven. Selleck appreciated the way "Magnum PI" portrayed Vietnam veterans in a positive light, which was unusual for television at the time. He fought for this aspect of the show when the studio initially balked. In "Blue Bloods," Selleck plays the head of a tight-knit family of law enforcement workers who learn more about each other with each episode.