This linguistic study contributes to the decades-long discussion on the inappropriateness of the Library of Congress Subject Heading illegal aliens by examining its absence in a corpus of US Supreme Court oral arguments and by evaluating automatic translation tool results related to keywords as well as a corpus extract. This linguistic study confirms the ideological bias of the illegal aliens subject heading compared to a plethora of other expressions that legal scholars may use to describe the situations implied under the more neutral umbrella term noncitizen. The automatic translation results for alien and illegal alien also support the notion that the term illegal alien is confined to a United States historical context, which hinders its international comprehension as a subject heading.