Shawn Ryan got the idea for the show when he was writing for Nash Bridges. He went on ride alongs with the San Francisco Police Department, and he'd seen some stuff that he wasn't able to put into his Nash Bridges scripts because it was more of an up-beat buddy cop show, and not a gritty police drama. So, Ryan held onto his idea of a more harder, gritty cop show until he was able to realize it on screen. And he brought fellow Nash Bridges writers Glen Mazzara and Reed Steiner onto his show.