Steve Fisher’s script was initially titled Invitation to a Hanging. Filmmaker Stanley Kramer protested the name, as it too closely resembled that of his upcoming film, Invitation to a Gunfighter (1964, see entry), the 29 May 1963 DV reported. The following month, a 17 Jun 1963 DV item indicated that the film had been re-titled The Day of the Hanging; however, a final title change to Law of the Lawless was announced in a 25 Jun 1963 DV brief.
       The 6 May 1963 DV announced the film as an upcoming A. C. Lyles production for Paramount Pictures release, with Rory Calhoun, William Bendix, Richard Arlen, and John Agar set to star. According to an article in the 31 Oct 1963 DV, per Lyles’s deal with Paramount, the producer likely financed the entire production budget, while Paramount provided studio facilities and handled distribution. Principal photography began 3 Jun 1963. Five months later, the 31 Oct 1963 DV reported the picture was “completed and awaiting release.” It first opened on 18 Mar 1964 in Los Angeles and San Francisco, CA, and Tucson, AZ. In Los Angeles, it played on a double bill with The Son of Captain Blood, and in New York it was shown with Robinson Crusoe on Mars (1964, see entries).
       The 23 May 1963 ^DV listed Jeanne Crain as a cast member, although it indicated a potential scheduling conflict for the actress. Various contemporary sources, including the 26 Jun 1963 DV, noted that Paul Dunlap was hired to compose the score.
       Law of the Lawless was said to be the first production to use Techniscope, described in a 21 Jun 1963 DV article as “Technicolor’s new photographic system” that promised to cut filming costs by fifty percent. DV explained the technology by stating the cost reduction “is effected by the negative frame of the camera being two perforations in height as against the usual method of four perforations. Thus, one-half the amount of negative is used.”