Under pressure from several pro-immigrant groups, the Library of Congress has decided to bar the use of the words "illegal" and "alien," choosing instead "noncitizens" and "unauthorized immigration" in its subject headings.

"In response to constituent requests, the Policy and Standards Division of the Library of Congress, which maintains Library of Congress Subject Headings, has thoroughly examined and discussed the status of the headings 'Aliens' and Illegal aliens.' PSD has determined that the heading 'Aliens' should be revised to 'Noncitizens.' The heading 'Illegal aliens' will be cancelled and replaced by two headings, 'Noncitizens' and 'Unauthorized immigration,' which may be assigned together to describe resources about people who are in a country illegally," said the library.

The changes announced this month will affect all libraries in the United States and Canada that use records distributed by the Library of Congress, according to the Migration Policy Institute, which highlighted the change in its Thursday newsletter.

The Library of Congress, funded by taxpayers, said that it studied the issue, considered the concerns of the groups seeking the change, and decided that the terms were "pejorative."

It said in a statement, "The phrase 'illegal aliens' has taken on a pejorative tone in recent years, and in response, some institutions have determined that they will cease to use it. For example, in April 2014 the Associated Press announced that illegal would not be used as a descriptor for any individual."

The move by the Policy and Standards Division of the Library of Congress is the latest step in the immigration debate to shift away from calling undocumented immigrants illegals.

The library detailed the discussion for the changes of each word. On "alien," for example, it noted that there had been confusion on the term and if it meant people from another planet.

"Because of the resulting confusion, PSD decided that it would be useful to reconsider the heading 'Aliens' during its reconsideration of 'Illegal' aliens," said the library.

The statement concluded, "The heading 'Aliens' will be revised to 'Noncitizens.' For 'Illegal aliens,' the meeting decided that a heading referring to the act of residing in a place without authorization should be used rather than a heading that describes the people as illegal or unauthorized. For resources about people who reside in a country without authorization, two headings will be assigned, 'Noncitizens' and 'Unauthorized immigration.'"

See the full statement here.

Paul Bedard, the Washington Examiner's "Washington Secrets" columnist, can be contacted at pbedard@washingtonexaminer.com