Blacklisting is the action of a group or authority compiling a blacklist of people, countries or other entities to be avoided or distrusted as being deemed unacceptable to those making the list; if people are on a blacklist, then they are considered to have done something wrong, or they are considered to be untrustworthy. As a verb, blacklist can mean to put an individual or entity on such a list.^[1] A blacklist is synonymous with a list of banned persons or organizations, and is the opposite of a whitelist.

The English dramatist Philip Massinger used the phrase "black list" in his 1639 tragedy The Unnatural Combat.^[2]

After the restoration of the English monarchy brought Charles II of England to the throne in 1660, a list of regicides named those to be punished for the execution of his father.^[3] The state papers of Charles II say "If any innocent soul be found in this black list, let him not be offended at me, but consider whether some mistaken principle or interest may not have misled him to vote".^[4] In a 1676 history of the events leading up to the Restoration, James Heath (a supporter of Charles II) alleged that Parliament had passed an Act requiring the sale of estates, "And into this black list the Earl of Derby was now put, and other unfortunate Royalists".^[5]

Edward Gibbon wrote in The History of the Decline and Fall of the Roman Empire (1776) of Andronicus that "His memory was stored with a black list of the enemies and rivals, who had traduced his merit, opposed his greatness, or insulted his misfortunes".^[6]

The first published reference to blacklisting of an employee dates from 1774. This became a significant employment issue in American mining towns and company towns, where blacklisting could mean a complete loss of livelihood for workers who went on strike.^[7] The 1901 Report of the Industrial Commission stated "There was no doubt in the minds of workingmen of the existence of the blacklisting system, though it was practically impossible to obtain evidence of it." It cited a news report that in 1895 a former conductor on the Atlantic and Pacific Railroad committed suicide, having been out of work ever since a strike: "Wherever he went, the blacklist was ahead of him".^[8]

Though the National Labor Relations Act of 1935 outlawed punitive blacklists against employees who supported trade unions or criticised their employers, the practice continued in common use. The Taft-Hartley Act of 1947 made amendments which sustained blacklisting by affirming the right of employers to be anti-union, and by requiring trade union leaders to make loyalty oaths which had the same effect as the Hollywood blacklist. Since then, lawsuits for unfair dismissal have led to blacklisting being covert or informal, but it remains common.^[7]

In 1981 following the PATCO workers' refusal to return to work, the Reagan administration fired the 11,345 striking air traffic controllers who had ignored the order,^[9][10] and banned them from federal service for life.

The Hollywood blacklist was an entertainment industry blacklist instituted in 1947 to block screenwriters and other Hollywood professionals who were purported to have Communist sympathies from obtaining employment. It started by listing 151 entertainment industry professionals and lasted until 1960 when it was effectively broken by the acknowledgement that blacklisted professionals had been working under assumed names for many years.^[11][12]

At least one Scottish volunteer (George Drever) in the International Brigades who went to Spain to fight Franco's fascists and who was also well known in the British Communist Party in the 1930s was informed by the police Special Branch that his failure to progress in military or career was due to his volunteering in this cause and his beliefs.^[13]

During World War I, the British government adopted a "blacklist" based on an Order in Council of 23 December 1915, prohibiting British subjects from trade with specified firms and individuals in neutral countries; the lists were published in the London Gazette.^[14]

In the summer of 1940, the SS printed a secret list^{[of what?]} called Sonderfahndungsliste G.B. ("Special Search List Great Britain") as part of Nazi Germany's preparations for invasion code-named Operation Sea Lion – when this booklet was found after the war, it was commonly called the Black Book and described as a blacklist.^[15]

In 1907, the Transvaal Medical Union in South Africa blacklisted patients if they could not pay cash in advance.^[16] There was a physical list kept by the community of physicians.

After the 2004 Venezuelan recall referendum, ruling party deputy Luis Tascón published on his website a database of more than 2,400,000 Venezuelans who had signed the petition to recall President Hugo Chávez, together with their national identity card numbers (cédula).^[17][18] The list "made sectarianism official", and Venezuelans who signed against Chávez were denied jobs, benefits, and documents, and often subjected to harassment.^[19] Once the list was posted, Chávez, on a Venezolana de Televisión broadcast, encouraged use of the website to "verify illicit use of national identity cards". Roger Capella, Minister of Health declared that "those who signed against President Chávez would be fired because they are committing an act of terrorism".^[20] There was a public outcry, in particular by the organization Súmate, and because of reports that people who worked for the government were fired, denied work, or denied issuance of official documents because of their appearance on the list.^[21][22] In July 2004, access to the database under management of Comando Maisanta was granted to members of the "Batallones Bolivarianos de Internet (BBI)" (Internet Bolivarian Battalions), which previously had to register on Tascón's website to gain access under the strict requisite that they had not signed the petition for the referendum.^[23]

In computing, a blacklist is an access control system that denies entry to a specific list (or a defined range) of users, programs, or network addresses.

• Lorence, James J. (1999). The Suppression of Salt of the Earth: How Hollywood, Big Labor, and Politicians Blacklisted a Movie in Cold War America. University of New Mexico Press. ISBN 0-8263-2027-9.