(CNN) The Department of Justice on Monday night forcefully disputed an account by the American Civil Liberties Union, Common Cause and others that the decision to add a citizenship question to the census was politically motivated.
A Justice Department spokesperson says the allegations that a 2015 study by a Republican redistricting expert played a major role in the request to add a citizenship question to the census are meritless.
In a letter last week, the ACLU, Common Cause and others said they had found "new evidence" that the government's true motivation in adding the question was to improve the chances of Republicans.
They pointed to a recently disclosed 2015 study written by Dr. Thomas Hofeller, a Republican redistricting expert, who wrote that using "citizen voting age" population as the redistricting population base would be "advantageous to Republicans and Non-Hispanic Whites."
The challengers say the new information shows Hofeller played a more significant role in the decision to add the citizenship question than has been disclosed and that his study reveals the true motive behind the administration's decision to add the question. Meanwhile, challengers in a separate case in Maryland, citing the Hofeller evidence, asked a federal judge on Tuesday to reopen their case to reconsider whether the Trump administration sought to intentionally discriminate against Latinos and immigrants.
The Justice Department ripped the allegations as a "baseless attack on the integrity of the Department and its employees," and a spokesperson said the allegations are based on information the challengers have known for months.
According to the spokesperson, the study by the now-deceased Hofeller "played no role in the Department of Justice's letter recommending reinstatement of a citizenship question to the Census." Hofeller died last August.
The Justice Department rebutted the allegations on Monday in a six-page letter, accompanied by multiple exhibits, to a federal judge in New York who has scheduled a hearing on Wednesday.
In the court filings, the department calls the claim that a Justice Department official relied on Hofeller's study "false."
In the filing, the Department of Justice said senior official John Gore had never falsely testified and "the assertion that Gore relied on a private, unpublished study to compile information that is widely known and publicly available is absurd."
The department accuses the challengers of "conjuring a conspiracy theory involving a deceased political operative that essentially hinges on wordplay."
District Judge Jesse Furman, of the US District Court for the Southern District of New York, ruled against the administration in January and in April the Supreme Court heard arguments in the case. A decision in one of the most closely anticipated cases of the term is due by the end of June.
The Supreme Court agreed to take up the appeal in an expedited time frame. In court, the conservative justices appeared ready to side with the government and allow the question.
In a letter to Furman, the challengers say the evidence bolsters their argument that while the administration contends the question was added to better comply with federal voting laws, the real reason was to intimidate Hispanic households.
"The new evidence thus not only contradicts testimony in this case, but it shows that those who constructed the VRA (Voting Rights Act) rationale knew that adding a citizenship question would not benefit Latino voters, but rather would facilitate significantly reducing their political power," the letter to the judge read.
The lawyers attached a copy of a deposition of A. Mark Neuman, who they say was Commerce Secretary Wilbur Ross' expert adviser on the matter, in their letter to the judge.
Neuman testified that Hofeller was the "first person" who suggested to him to add the citizenship question. Neuman said in the deposition that Hofeller had told him it would help maximize "Latino representation."
"But new evidence obtained in discovery in state court ... shows that Dr. Hofeller instead knew that adding a citizenship question would have exactly the opposite effect -- it would disadvantage Latinos and benefit 'Non-Hispanic Whites,' " the lawyers told the judge.
They also say that Hofeller "ghostwrote" a "substantial part" of a draft letter that would ultimately become the Department of Justice's official letter requesting that the Commerce Department add the citizenship question.
"This is important because it shows that Hofeller's work formed the basis for DOJ's request to add the citizenship question," said ACLU attorney Dale Ho.
"The bottom line is the Trump administration doesn't deny that portions of its first draft of a request to add a citizenship question to the census were written by Thomas Hofeller, who advocated for the question because it would be, in his own words, 'advantageous to Republicans and Non-Hispanic Whites,' " Ho said in a statement. "At this point, does anyone seriously believe that the Trump administration, which hasn't filed a single case under the Voting Rights Act, has gone through all of this trouble so that it can protect voters of color?"
The information came to light after Hofeller had passed away and his estranged daughter collected his belongings. They included a hard drive that turned out to hold some 75,000 files.
The interest group Common Cause was involved in a case concerning gerrymandering in North Carolina and subpoenaed the documents hoping to get a better understanding of Hofeller's work in that area. It then found the documents pertinent to its other case concerning the census.
Richard Hasen, of the University of California Irvine, called the new information "blockbuster" but said he doubted the conservative justices on the Supreme Court would agree. He noted that during oral arguments they had accepted at "face value" the administration's justification for the law, that the question was "necessary to protect Hispanic voters."