The D.A. starred Robert Conrad as Deputy District Attorney Paul Ryan, a tough-minded, hard-hitting prosecutor in Los Angeles County who was assisted by criminal investigator Bob Ramirez (Ned Romero). He prosecuted all types of cases under the watchful eye of his supervisor, Chief Deputy District Attorney "Staff" Stafford (Harry Morgan). His opponent was usually Public Defender Katherine Benson (Julie Cobb). During the courtroom segments Ryan also provided a voice-over narration (like Dragnet), which brought the audience in on legal jargon and court procedures and allowed there to be less exposition in the dialogue, which was necessary due to the program's brevity as most legal dramas have episodes twice the length of that of The D.A..
This program, however, is probably less known for its own storylines than for its lack of station clearances. Several NBC affiliates didn't even bother to clear the program, choosing instead to take the time period for themselves, with the result that NBC soon replaced it with the highly successful Sanford and Son.
It was produced by Jack Webb's Mark VII Productions for Universal Studios. The series was spun off from an episode of Adam-12 in which officers Malloy (Martin Milner) and Reed (Kent McCord) made an arrest and Ryan then handled the eventual prosecution.
In 1990, producer Dick Wolf dusted off the half-investigation, half-trial format of The D.A. and modified it for his hour-long detective drama Law & Order by eliminating the narration but utilizing instead a Dragnet-style dialog between characters. The D.A. was not the first broadcast network series to use the format: Arrest and Trial's 90-minute episodes predate The D.A. by eight years.