During the Red Scare, blacklisting was a practice of creating a list of individuals whose opinions or associations were deemed politically inconvenient or commercially troublesome, thereby subjecting them to difficulty finding work or termination from employment. In Hollywood, the blacklist was implemented by the studios to promote their patriotic credentials in the face of public attacks and served to shield the film industry from the economic harm that would result from an association of its product with subversives. The blacklist was rarely made explicit or easily verifiable, as it was the result of numerous individual decisions by the studios and was not the result of official legal action. The blacklist was created by producers who instituted compulsory oaths of loyalty from their employees with the threat of a blacklist. The blacklist was enforced by non-governmental organizations, including the American Legion, a conservative war veterans group, which was instrumental in pressuring the entertainment industry. Those who were blacklisted were barred from employment in most of the entertainment field. Some of those blacklisted continued to write for Hollywood or the broadcasting industry surreptitiously, using pseudonyms or the names of friends who posed as the actual writers. The blacklist lasted until 1960, when Dalton Trumbo, a member of the Hollywood Ten, was credited as the screenwriter of the film Exodus (1960), and publicly acknowledged by actor Kirk Douglas for writing the screenplay for Spartacus (also 1960) .