What Lontine did not know, however, was that for more than 13 years, the words have also resided in an arcane section of the Colorado state code about who can work on public projects. A friend recently came across the language while training for her job with the City of Denver.

“She goes, ‘Why are you using that? That’s an awful term,’ ” Lontine said in a recent interview.

Lontine looked up the law herself and was surprised to see the words there.

Then, she thought, what if they weren’t?

Lontine plans to introduce a bill this month that would remove the term “illegal aliens” from the law and replace it with the more neutral “undocumented immigrants,” saying that changing the words could bend social sentiment in migrants’ favor. And with Democrats now in control of the Legislature and the governor’s office, the bill may face relatively few hurdles.

But it comes as the conservative news media has increasingly broadcast messages that demonize immigrants, in part echoing President Donald Trump’s scathing rhetoric on immigration; he used the term “illegal alien” at least five times during the State of the Union this month.

Some conservatives argue that terms like “illegal aliens” are fair and universally understood, having been used for decades by lawmakers, judges and newspapers. But for others, there is a growing awareness that the terms denigrate immigrants by branding humans — as opposed to actions — as illegal.

The debate is playing out at an increasingly granular level, with politicians wrestling over the words etched into laws and official government discourse. California in 2015 removed the word “alien” from its labor code. The New York City Council is considering a new bill that would replace “alien” with “noncitizen” and bar the city from using “alien,” “illegal alien” or “illegal immigrant” in city laws or documents.

At the national level, U.S. Rep. Joaquin Castro, D-Texas, introduced a bill in July that would replace “alien” and “illegal alien” with “foreign national” and “undocumented foreign national” in one of the country’s main immigration laws.

By contrast, the Justice Department sent a memo to federal prosecutors reminding them to use “illegal aliens” instead of “undocumented” in news releases, CNN reported in 2018.

“The word ‘undocumented’ is not based in U.S. code and should not be used to describe someone’s illegal presence in the country,” the memo said.

Jose Antonio Vargas, who founded Define American, a nonprofit based in Louisville, Kentucky, that advocates for migrants, said that “the language we use determines the nature of the conversation.”

Vargas, who immigrated to the San Francisco Bay Area illegally in 1993, remembers the words “resident alien” being stamped on a fraudulent green card his grandfather bought him. Several years later, he read the words “illegal aliens” in a front-page newspaper article and heard it on the radio while heading to school.

“Terms like ‘alien’ and ‘illegal,’ which I grew up hearing on the radio and TV and reading in newspapers and magazines, had an isolating, disorienting, dehumanizing effect,” Vargas said.

While the terms have not always been so polarizing, they have traditionally been used to strip people of personhood and subject them to legal punishments, said Kevin Johnson, dean of the law school at the University of California, Davis, who has researched the history of the terms.

He said the word “alien” had been used since the country’s founding to describe any noncitizen — the British, for example. The notorious Alien and Sedition Acts, passed in 1798, tightened restrictions on Americans born outside the country and limited speech critical of the government.

In 1924, the country adopted a quota system for immigrants based on national origin, giving rise to the idea that there were unwanted, “illegal” immigrants, said Mae Ngai, a history professor at Columbia University. But still, she said, the term “illegal alien” was mostly associated with prohibition and smuggling.

In the mid-20th century, policies targeting migrants from Mexico furthered the idea of “illegal aliens,” Ngai said.

Usage of the term and others like it spiked in the 1970s and 1980s as immigrants grew to become a larger slice of the U.S. population. Civil rights groups, particularly Mexican American activists, increasingly fought those labels, Ngai said.

“These terms also become fraught because they associate so-called illegality or criminal status to a person as opposed to an act,” she said.

In recent years, there has been more focus on the effect of the words. A 2009 opinion written by Supreme Court Justice Sonia Sotomayor was the first to use the term “undocumented immigrant,” which the justice has said she used to recognize that immigrants who break the law are not necessarily bad people.

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The Associated Press, which publishes a stylebook that guides hundreds of news outlets, decided in 2013 to stop using “illegal” to describe a person, arguing that only actions are illegal.

The New York Times does not use “alien” but will use “illegal” to refer to immigrants without legal status, as well as “undocumented” and “unauthorized.” The Times’ stylebook also suggests using language that directly describes the specific circumstances of a person as a way to avoid using those terms altogether.

There has been backlash against attempts to change the language. Some conservative politicians, seeking to push aggressive policies targeting immigrants, frequently use terms like “illegals,” “illegal immigrants” and “illegal aliens.”

In 2016, after activism from a group of Dartmouth students, the Library of Congress said it would remove “alien” and “illegal alien” from subject headings and replace the terms with “noncitizens” and “unauthorized immigration.” But the library reversed course under pressure from House Republicans.

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Alex Nowrasteh, director of immigration studies at the Cato Institute, said he favored policies allowing most people who immigrated illegally to stay in the country. But he said advocacy around terms like “illegal alien” distracted from actual policy debates.

“There’s a segment of people who want to call people illegal immigrants, undocumented immigrants, as part of either not offending people or as a marketing technique,” Nowrasteh said. “I think it’s a total waste of time.”

Nowrasteh said he did not think changing the words would change anyone’s mind, noting that a number of terms, including “illegal alien,” have been used dozens of times in federal immigration law.

“What matters is how people actually feel and whether it actually causes confusion,” he said. “The point of language is to communicate. If we’re all using different terms to mean the same thing, we can’t communicate as well.”

Vargas, however, said that language could and should evolve. Other pejorative terms have been removed from government documents as people better understood the hurtful connotations.

Instead of “illegal alien,” Vargas prefers any term that precisely describes an act as illegal and not a person, such as “unauthorized” immigrants or “people who are here illegally.”

“I am for any kind of language that actually describes what is happening and treats people like human beings,” he said.

This article originally appeared in The New York Times .