New York State Attorney General Barbara Underwood's office may move forward with its plan to depose a key U.S. Department of Justice official in its lawsuit over the citizenship question on the 2020 U.S. Census, the U.S. Second Circuit Court of Appeals decided late Tuesday.

Testimony from acting assistant attorney general for the Civil Rights Department John Gore could be an important step for investigators to figure out who was behind the citizenship question. He allegedly ghostwrote a letter from the Department of Justice to Commerce Secretary Wilbur Ross last year asking that the question be added.

Gore could also help shed light on what motivated officials in the Trump administration to add the question, which was announced earlier this year. Spokespeople for the departments of commerce and justice did not immediately respond to a request for comment on the Second Circuit decision. Kate Bailey is the lead attorney for the Trump administration in the case.

A spokeswoman for Underwood's office said the decision will help their case move forward.

“We welcome the court's decision—and we'll get to the bottom of how the decision to demand citizenship status was made, as we continue our case to ensure a full and fair census,” said Amy Spitalnick, spokeswoman for Underwood.

Gore's deposition was originally scheduled for earlier in September but it was stayed pending a decision from the Second Circuit on a July decision from U.S. District Judge Jesse Furman of the Southern District of New York that allowed discovery to proceed in the case.

Furman also allowed extra-record discovery in that decision, saying there was “strong” evidence the Trump administration acted in bad faith when deciding to add the citizenship question. The Trump administration had petitioned for a writ of mandamus on the decision, or a review by the higher court.

The Second Circuit also denied that request in their decision late Tuesday, which means discovery in the lawsuit can continue as it was.

“The district court applied controlling case law and made careful factual findings supporting its conclusion that the initial administrative record was incomplete and that limited extra-record discovery was warranted,” the Second Circuit decision said.

Underwood's office has been quickly making their way through several Trump administration officials who have testified that there were conversations about adding a citizenship question to the census in the early months of 2017—almost a year before it was announced. Those officials have also repeatedly said they do not have direct knowledge of discussions between top Trump administration officials over the citizenship question, according to transcripts included with filings.

That's why Underwood's office asked Furman to compel the deposition of Ross, who officials said would be one of few individuals privy to such conversations. Furman ordered Ross to sit for the deposition in a decision last week. That deposition has not been scheduled.

The lawsuit has been tentatively scheduled to go to trial on Nov. 5, though Furman accepted a brief from the Trump administration last week explaining why the case should be decided by summary judgment. He has not made a final decision on whether the case will go to trial, but remarks in court seemed to suggest he would have to be convinced otherwise.

Underwood's office said in its own filing last week that the case should go to trial to show the motivation of Trump administration officials in adding a question about citizenship to the census.

Her office is leading a coalition of 18 state attorneys general in the lawsuit, which was filed in April shortly after the citizenship question was announced.

The attorneys general have argued that asking about citizenship will decrease turnout for the census in states with large immigrant populations, like New York. That could have a ripple effect by causing those states to lose representatives in Congress and the Electoral College. The attorneys general also argued that a smaller recorded population could mean less federal funding in areas like education and health care.

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