The drama revolves two seemingly unrelated high-profile murder cases and the subsequent police investigation, arrest and trial, offering viewers a window into the inner-workings of modern justice in an increasingly complex world.
Diggs will play Terry Seagrave, said to be a homicide detective who is dealing with his wife's terminal illness.
For Terry, being a cop is his one chance to live right and "do good," and the job keeps him focused and off the sadness that tends to preoccupy his thoughts.
Bochco, who's had a few hit crime drama TV series on his resume, will pen the pilot with Eric Lodal (Lawless) and executive produce.
Diggs lands this role just as ABC's Shonda Rhimes medical drama Private Practice, ended its run in January.
He's also part of an ensemble cast in the upcoming feature dramedy Larry Gaye: Renegade Male Flight Attendant, as well as the sequel to The Best Man, titled The Best Man Holiday.