Public enemy is a term which was first widely used in the United States in the 1930s to describe individuals whose activities were seen as criminal and extremely damaging to society, though in fact the term had been used for centuries to describe pirates and similar outlaws.
The modern use of term was first popularized in April 1930 by Frank J. Loesch, then chairman of the Chicago Crime Commission, in an attempt to publicly denounce Al Capone and other Organized crime gangsters.
It was later appropriated by J. Edgar Hoover and the FBI who used it to describe various notorious fugitives that they were pursuing throughout the 1930s, as portrayed in the 2009 film Public Enemies. Among the criminals whom the FBI called "public enemies" were John Dillinger, Baby Face Nelson, Bonnie and Clyde, Pretty Boy Floyd, Ma Barker, and Alvin Karpis.
The term was used so extensively during the 1930s that some writers call that period of the FBI's early history the "Public Enemy Era". Use of the term eventually evolved into the FBI Ten Most Wanted Fugitives list.
As stated previously, Frank J. Loesch first used the term "Public Enemy" in the title of a list he wrote of Chicago's most prominent and influential gangsters.
All of those listed were reputed to be gangsters or racketeers and most were rum-running bootleggers. Although all were known to be consistent law breakers (most prominently in regard to the widely broken Eighteenth Amendment to the United States Constitution (law banning alcohol)) none of those named were fugitives or were actively wanted by the law. The list's purpose was clearly to both shame those named and spur the authorities to prosecute them.
In 1933, Loesch recounted the origin and purpose of the list:
However unlike Loesch's use of the term, the FBI's "Public Enemies" were wanted criminals and fugitives who were already charged with crimes.
The FBI's website describes the bureau's use of the term: "[The] FBI and the United States Department of Justice made use of the term, "public enemy," in the 1930s, an era in which the term was synonymous with "fugitive" or "notorious gangster." It was used in speeches, books, press releases, and internal memoranda.