(CNN) A highly unusual and racially charged episode from the 2016 campaign suddenly resurfaced this week when a federal judge whom President Donald Trump repeatedly criticized was assigned to hear the case of a man who claims he was improperly deported.

Judge Gonzalo Curiel, who was born in the US but is of Mexican heritage, was attacked by Trump last year over his handling of a lawsuit against Trump University. Trump claimed Curiel could not impartially hear the case because of his background and Trump's hardline immigration policies. The case was eventually settled.

Now, Curiel is assigned to hear the case of Juan Manuel Montes Bojorquez, 23, who his lawyers allege was deported from California to Mexico earlier this year despite having active protection under the Deferred Action for Childhood Arrivals program, also known as DACA.

And Trump's comments toward Curiel last year -- he called the Indiana-born judge a "hater" and a "Mexican" -- drew some of the loudest accusations of racism that the then-candidate faced during his campaign and several repudiations from prominent Republicans.

The lawsuit, which is brought under the Freedom of Information Act, has already become a flashpoint in the Trump administration's immigration policy and the President's murky position on DACA.

Curiel's involvement is sure to increase the publicity surrounding the case, which is already shaping up to be one of the more high-profile challenges to execution of Trump's immigration agenda. The White House did not immediately respond to an inquiry about whether the President feels Curiel will be a fair judge in the matter.

Shifting positions on DACA

The President's own position on DACA has evolved. Trump pledged to end DACA during the 2016 campaign, but the Department of Homeland Security has continued issuing permits and he has since spoken about how sympathetic he finds the people in DACA -- undocumented immigrants brought to the US as children who, in many cases, know no other home.

"We're going to show great heart," Trump said at a news conference in February. "DACA is a very, very difficult subject for me, I will tell you."

But he also spoke of possible abuses of the DACA program in the same thought, saying in "some of the cases, having DACA and they're gang members and they're drug dealers, too. But you have some absolutely, incredible kids, I would say mostly. They were brought here in such a way -- it's a very -- it's a very, very tough subject."

Homeland Security Secretary John Kelly has insisted the administration has not detained or deported anyone with an active DACA status, but several former DACA recipients have been detained and, in some cases like Montes', the government has maintained that a violation of the program forfeited the status.

Lawyers for Montes say their client was apprehended by Border Patrol and deported on February 18. DHS said Wednesday that never happened.

While DHS initially said Tuesday they had a record of Montes' DACA status expiring in 2015, they released further information Wednesday saying he did, in fact, have DACA status until 2018, agreeing with lawyers for Montes.

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The problem, though, is on the part of the story both sides agree on: Montes tried to sneak back into the US on February 19 and was caught by Border Patrol. DACA requires individuals to get pre-clearance to leave the country, and so Montes' re-entry then showed he had left without authorization and voided his status, DHS said. He was sent back to Mexico the following day, where he is now staying.

The administration has said that it respects DACA and that no one with active status would be deported, but advocates are using the Montes case and others to call into question whether DHS is being honest about its position.

The lawsuit is seeking records about Montes' interactions with Customs and Border Patrol, and also any appropriate relief for Montes including attorney fees.

'The definition of racism'

Trump was condemned by Democrats and Republicans alike last year after he criticized Curiel's rulings in the Trump University case and attacked Curiel personally.

One of Trump's harshest rebukes came from House Speaker Paul Ryan, who described the language as "sort of like the textbook definition of a racist comment." Senate Majority Leader Mitch McConnell called Trump's remarks "offensive and wrong" and former House Speaker Newt Gingrich, a staunch ally of Trump, called the comments "inexcusable" and "one of the worst mistakes Trump has made."

Trump later defended himself in a written statement, saying he did not believe "one's heritage (made) them incapable of being impartial."

"Based on the rulings that I have received in the Trump University civil case, I feel justified in questioning whether I am receiving a fair trial," Trump said. He also referenced "the core issues of my campaign that focus on illegal immigration, jobs and unfair trade" in explaining his criticism.

In a memorable exchange with CNN's Jake Tapper in June, Trump vociferously -- and repeatedly -- defended his claims that Curiel was biased.

"He's proud of his heritage. I respect him for that," Trump said, dismissing charges that his allegation was racist. "He's a Mexican. We're building a wall between here and Mexico."

At the end of a lengthy exchange, Tapper asked: "If you are saying he cannot do his job because of his race, is that not the definition of racism?"

"No, I don't think so at all," Trump said.