The US Department of Justice wants US attorneys offices to stop referring to immigrants as “undocumented,” the term that media and immigrant advocates have increasingly used to refer to people who are in the country illegally.

The DOJ now wants government lawyers to use “illegal alien,” according to an email obtained by CNN. “The word ‘undocumented’ is not based in US code and should not be used to describe someone’s illegal presence in the country,” the email says.

The directive is the Trump administration’s latest rule about how the government talks about immigrants. Earlier this year, US Citizenship and Immigration Services, the agency that processes green cards, removed the phrase “a nation of immigrants” from its mission statement. That agency also renamed the Citizenship and Integration Grant Program, which funds English and civics classes for citizens, to the Citizenship and Assimilation Grant Program.

How to refer to people who are in the US without the necessary paperwork was controversial before the DOJ weighed in. Immigrant advocates say that calling anyone “illegal” dehumanizes them, and fails to take into account the extraordinary circumstances of refugees. Some newsrooms have opted for “undocumented.” Like the DOJ, groups that favor reducing immigration argue that “undocumented” is not mentioned in the legal code.

“[The term ‘undocumented’] blurs the distinction between legally admitted immigrants and those who have sneaked into the country or chosen to violate the terms of a legal entry,” says one anti-immigration activist group, the Federation for American Immigration Reform, on its website.

But their preferred term, “illegal alien,” isn’t very prominent in the US legal code either, according to fact-checker Politifact Texas. Although it makes a few appearances, it’s mostly on section titles, not in the text of the law itself. In the Immigration and Nationality Act, “illegal alien” is only used to refer to immigrants who have been convicted of a felony.

The most common wording used in US laws to describe people who don’t have permission to be in the country is actually “inadmissible aliens.”