Supporters of President Trump hold a counter protest while immigration rights activists march during a May Day rally in Los Angeles, Calif. (Eugene Garcia/EPA)

Immigration hard-liners whose fortunes are rising under the Trump administration have released a confidential year-old letter from the Justice Department’s immigration court that blasted left-leaning lawyers for targeting them with “derogatory name-calling” based on a report by the Southern Poverty Law Center.

At issue was the SPLC’s repeated claim that the Federation for American Immigration Reform is a “hate group” as well as its escalating efforts to prove that the federation, which favors stricter control over legal and illegal immigration, is racist.

The immigration court’s letter — sent during the Obama administration — does not resolve that dispute. But the decision to release it illuminates the fight for credibility in the national immigration debate, with both sides emboldened after the election of President Trump.

Advocates for immigrants, who have won key victories to block Trump’s immigration crackdown in court, would like the government not to consider the views of the federation and its allies, whose leaders have made statements that critics say evoke racism.

Demonstrators marching to protest President Trump's immigration policies during the "Immigrants Make America Great March" in Los Angeles, Calif. (Mark Ralston/AFP/Getty Images)

But the federation and other critics of illegal immigration say they do not discriminate and are fueled by concern about jobs and resources for Americans. Trump has embraced many of their views and is appointing top officials whom they count as allies, including former federation director ­Julie Kirchner, recently named ombudsman for U.S. Citizenship and Immigration Services.

“What [immigrant advocates] want is to delegitimize all skepticism of the open-borders, globalist immigration model, as if such a position can never be legitimate for America,” said Dale L. Wilcox, executive director and general counsel of the Immigration Law Reform Institute, the federation’s legal arm.

“They label as morally deficient concerned citizens who happen to worry that there’s a connection between things like immigration and urban sprawl or increased labor supply and lower wages.”

Wilcox released a letter dated March 28, 2016, from the immigration court’s disciplinary counsel, Jennifer J. Barnes, that resolved a dispute about whether the federation should be allowed to file friend-of-the-court briefs on issues before the Board of Immigration Appeals. The board had asked the federation and the American Immigration Lawyers Association to weigh in on cases for years, including in 2014 and 2015.

Lawyers for the SPLC and for groups representing immigrants involved in the cases objected to the request for input from the federation, arguing that it is a “hate group,” “white supremacist,” “eugenicist,” “anti-immigrant,“anti-Semitic” and “anti-Catholic,” the court’s letter said.

The federation called those descriptions “McCarthyite ad hominem attacks” and asked the board to sanction the lawyers.

In response, Barnes issued a four-page rebuke of the SPLC’s lawyer and three others from immigrant advocacy groups. She said their efforts were “frivolous behavior” that “overstepped the bounds of zealous advocacy.”

“None of this language was related or relevant to the underlying factual or legal matters or FAIR’s amicus briefs, and its sole purpose was to denigrate FAIR and its staff,” she wrote, using an acronym for the federation. “Such language is not appropriate in a filing before the Board.”

Barnes asked the lawyers to keep the letter confidential, and did not open a formal disciplinary proceeding. The lawyers said they took the letter as an informal reprimand.

Wilcox said his organization, which wants to slash legal immigration from about 1 million people a year to 300,000 a year, an idea also floated by Trump and conservative members of Congress, did not initially consider releasing the letter. Then the SPLC added the federation’s legal arm to its formal list of “hate groups” this year. In response, the federation filed a complaint with the IRS against the SPLC, accusing it of violating its tax-exempt status by engaging in political activity, which the SPLC denied.

Richard Cohen,president of the SPLC, saidhis group researched the published papers and remarks of foundation founder John Tanton and other foundation officials and published them on its website. Among the many examples are a 1993 Tanton letter that said he favored a “European-American majority” in the United States. He also published a journal that critics said featured racist texts.

Cohen said the SPLC typically labels as hate groups those that “vilify entire groups of people” based on characteristics such as race, religion, ethnicity or sexual orientation.

“The question is whether they are a biased advocate. Are their positions infected with racism?” Cohen said. “We would say yes.”

The four lawyers targeted by the foundation’s complaints to the appeals board said Barnes never notified them about the criticism or gave them a chance to respond.

The foundation also filed state bar complaints against the four lawyers. Cohen and the other lawyers said the bar complaints were dismissed.