Dragnet is an American radio, television and picture series, enacting the cases of a dedicated Los Angeles police detective, Sergeant Joe Friday, and his partners. The show takes its name from the police term "dragnet", meaning a system of coordinated measures for apprehending criminals or suspects. Actor and producer Jack Webb's aims in Dragnet were for realism and unpretentious acting.
When television was interested in Dragnet, Webb bucked the prevailing argument that radio staff could not adapt to the new medium. He insisted on hiring actors, writers, and production staff from radio as much as was feasible to work on the television version. This loyalty would endear Webb to many Dragnet colleagues for decades to come, but more important was that it brought continuity between the television and radio series. This made it possible for a busy person to listen to the audio and get the whole story.
Television offered Webb the opportunity to increase realism to a point unmatched by any other program for years. Many early episodes involved cases handled by the Robbery or Homicide Divisions, located in the ground floor of the Los Angeles City Hall. Webb's set designers duplicate the office, including details like the remnant of a notice torn from the bulletin board, leaving only one corner. He insisted that Friday and his partner use badges in the unique shield shape used by LAPD. This led to the loan of LAPD badges, brought in every morning from the Office of the Chief of Police in the care of an officer who acted as technical advisor. (Source: wikipedia.org)