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Controversies in the Library of Congress Subject Headings (LCSH): the Case of Illegal Aliens

Library of Congress Subject Headings (LCSH) includes some headings which are considered pejorative, disrespectful or biased by some people. In this article, we shall discuss one such LCSH heading "Illegal Aliens."


  • Introduction to the Library of Congress Subject Headings (LCSH)
  • Controversies in the Library of Congress Subject Headings (LCSH): the Case of Illegal Aliens
    • Illegal aliens
      • Screenshots of the heading Illegal aliens in LCSH from the Library of Congress Website
    • Background
    • Subsequent Developments
    • Change the Subject - a Documentary
      • The project
      • Change the Subject Movie Trailer
  • Conclusion


Library of Congress Subject Headings (LCSH) is the list of headings produced from the subject authority file maintained by the United States Library of Congress for use in bibliographic records. It is popularly known by its abbreviation as LCSH and is sometimes used interchangeably with the phrase subject authority file. LCSH is a controlled vocabulary. A single word or phrase is chosen to represent each concept that is included, and synonyms are provided as see-references to that heading. It also indicates relationships between and among headings. It is not a true thesaurus, though, because for historical reasons it does not completely conform to the international standard on thesaurus construction. LCSH comprises the complete alphabetic list of terms to be used as controlled vocabulary for subject concepts by the catalogers of the Library of Congress and other libraries to provide such controlled subject access to surrogate records. LCSH has been used in cataloging since 1898 at the Library of Congress in assigning subject headings to facilitate subject access to the resources in its library catalog.

LCSH is a multidisciplinary vocabulary that includes headings in all subjects, from science to religion, to history, social science, education, literature, and philosophy. It also includes headings for geographic features, ethnic groups, historical events, building names, etc. Library of Congress Subject Headings (LCSH) is the most widely used subject vocabulary in the world. 

Library of Congress Subject Headings LCSH

LCSH comprises a thesaurus or a controlled vocabulary of subject headings which is used by a cataloger or an indexer to assign subject headings to a bibliographic record to represent the subject of a work he/she is cataloging. LCSH contains the preferred subject access terms (controlled vocabulary) that are assigned as an added entry in the bibliographic record which works as an access point and enables the work to be searched and retrieved by subject from the library catalog database. The controlled vocabulary identifies synonym terms and selects one preferred term among them to be used as the subject heading. For homonyms, it explicitly identifies the multiple concepts expressed by that word or phrase. Cross-references are used with headings to direct the user from terms not used as headings to the term that is used, and from broader and related topics to the one chosen to represent a given subject.

The fortieth edition of Library of Congress Subject Headings (LCSH 40) contains headings established by the Library through January 2018. The headings included in this list were obtained by creating a file consisting of all subject heading and subdivision records in verified status in the subject authority file at the Library of Congress. There were 342,947 authority records in the file then.

The subject authority database from which the headings in this edition were drawn indicates that the file contains approximately 24,390 personal name headings of which 23,272 represent family names, 10,034 corporate headings, 6 meeting or conference headings, 481 uniform titles, 242,511 topical subject headings, and 61,885 geographic subject headings. There are 764 general USE references, 4,351 general see also references, 299,751 references from one usable heading to another, and 362,646 references from unused terms to used headings.


Crystal Vaughan in her article The Language of Cataloguing: Deconstructing and Decolonizing Systems of Organization in Libraries⁶ writes: "As society, politics, and economies change, so too does the language of representation. Therefore, the Library of Congress subject headings (LCSH) as a system of categorization is only as effective as the language that is used to define what is and what is not. Moreover, those who control the language of categorization control access to the information categorized within that system. Consequently, librarians must always be critical of the language they are using in their information organization systems. Language is continuously evolving according to societal discourse and politics; therefore, if libraries are to maintain their social responsibility to provide information to all, including socially disadvantaged and marginalized peoples, then librarians must continuously advocate for changes to subject headings. Librarians must also recognize and reflect on their own internal biases when cataloguing and make it their job to deconstruct language and decolonize the systems that perpetuate the continued marginalization of others ...  Despite the many changes that have been implemented in the LCSH, there are still many LCSH that marginalize and dehumanize vulnerable, disadvantaged, and/or minority populations, which therefore restricts their access to information. If libraries are to maintain their social responsibility to provide information to all, including socially disadvantaged and marginalized peoples (IFLA, 2012)⁷, then librarians must continue to advocate for changes to politically charged or controversial subject headings. "

Illegal aliens

“Illegal aliens” is a controversial LCSH heading that is used for undocumented immigrant persons who are not citizens of the country in which they reside.

For many years, the Library of Congress categorized many of its books under a controversial subject heading: “Illegal aliens.”⁴

Screenshots of the heading Illegal aliens in LCSH from the Library of Congress Website

LCSH heading - Illegal aliens
LCSH heading - Illegal aliens [Source: Library of Congress Authorities]

LCSH heading - Illegal aliens
LCSH heading - Illegal aliens [Source: Library of Congress Linked Data Service]


In 2013, Dartmouth undergraduate and former undocumented immigrant, Melissa Padilla, came across the current LCSH “Illegal aliens” while doing research. Angered, Padilla stated the term is essentially used to “criminalize the choices our parents made in order to provide us with better lives,” and is meant to demean Mexican immigrants specifically. Padilla brought up the issue with Dartmouth students at a meeting of the Coalition for Immigration Reform, Equality and Dreamers, which, with the help of Dartmouth librarians, submitted a formal request to LC in 2014 to replace the term “Illegal aliens” with “Undocumented immigrants.” In February 2015, LC publicly responded that it would not change the heading. Following discussions in ALA including within the Subject Analysis Committee (SAC), Social Responsibilities Roundtable, and REFORMA, ALA formulated a resolution asking LC to reconsider the original request, arguing that “aliens” and “Illegal aliens” are pejorative terms.⁸

In 2016, the Library of Congress announced that it would reconsider the usage of “Aliens” and its related terms in the Library of Congress Subject Headings, following a student-led movement to change the pejorative term “Illegal Aliens.” Yet, three years on, these terms remain in the LCSH.⁵

On March 22, 2016, the library made a momentous decision, announcing that it was canceling the subject heading “Illegal aliens” in favor of two new headings: “Noncitizens” and “Unauthorized immigration.”

Following the announcement, Republican lawmakers made multiple attempts to block the revision of the subject heading, including the introduction of a bill by U.S. Representative Diane Black requiring the Library to retain the heading. In June 2016, the House of Representatives added a provision to the 2017 appropriations bill for the legislative branch requiring LC to retain the heading without revision. While the final bill did not require LC to keep the "Illegal aliens" wording, it did require LC "to make publicly available its process for changing or adding subject headings."--Violet B. Fox in Wikipedia.⁽⁹⁾

This was the first time Congress ever intervened over a Library of Congress subject heading change. Even though many librarians and the American Library Association opposed Congress’s decision, “Illegal aliens” remain the authorized subject heading today.

Cataloging and classification are critical to any library. Without them, finding materials would be impossible. However, there are biases that can result in patrons not getting the materials they need.

Subsequent Developments

The 2019 documentary film Change the Subject has been screened throughout the U.S. Over forty libraries and library systems have revised the heading in their own library systems.⁽⁹⁾

Change the Subject - a Documentary

The Project

Change the Subject shares the story of a group of college students, who from their first days at Dartmouth College, were committed to advancing and promoting the rights and dignity of undocumented peoples.  In partnership with staff at Dartmouth, these students – now alumni – produced a film to capture their singular effort at confronting an instance of anti-immigrant sentiment in their library catalog.  Their advocacy took them all the way from Baker-Berry Library to the halls of Congress, showing how an instance of campus activism entered the national spotlight, and how a cataloging term became a flashpoint in the immigration debate on Capitol Hill.

Year: 2019
Runtime: 54 minutes
Language: English
Country: United States

Change the Subject - Movie Trailer

Change the Subject is a must-watch documentary for all the lovers of LCSH who want to see it free from all the pejorative, disrespectful or biased headings.


Even after all the criticisms, LCSH is the most used subject headings list in libraries all around the world. Its usage and adoption by libraries have been increased by leaps and bounds since it is made available free by the Library of Congress. It remains a model for many other vocabularies in English and other languages. The strongest aspect of LCSH is that it represents subject headings of the Library of Congress, the national library of the United States, one of the richest national libraries in the world. The administrative and managerial machinery of LC has made it possible for LCSH to stand out as an undisputed leader.

  • We are thankful to Violet B. Fox for her suggestions to make important revisions/corrections to this article.



    1. Library of Congress, "LCSH Introduction," (accessed February 22, 2019).

    2. Janis L. Young and  Daniel N. Joudrey, Library of Congress, "Library of Congress Subject Headings: Online Training," (accessed March 17, 2020).

    3. Dartmouth College, "Change the Subject," (accessed April 1, 2020).

    4. Amanda Ros, The Conversation, "The bias hiding in your library," (accessed April 1, 2020).

    5. Grace Lo, "“Aliens” vs. Catalogers: Bias in the Library of Congress Subject Heading," Legal Reference Services Quarterly, 38, no. 4 (2019) (accessed April 1, 2020).

    6. Crystal Vaughan, "The Language of Cataloguing: Deconstructing and Decolonizing Systems of Organization in Libraries," DJIM, 14 (2018). 

    7. International Federation of Library Associations and Institutions (IFLA).(2012, August). IFLA code of ethics for librarians and other information workers (full version). Retrieved from

    8. Providing alternative subject headings for controversial Library of Congress subject headings in the Alliance shared ILS: Discussion paper by the Alliance Cataloging Standing Group.

    9. Wikipedia, "Illegal aliens (Library of Congress Subject Heading)," (accessed April 23, 2021).

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