A federal judge blocked the Commerce Department on Tuesday from adding a question on American citizenship to the 2020 census, the first ruling in a several lawsuits that claimed the query will hurt immigrants and accused the Trump administration of trying to turn the census into a tool to advance Republican political fortunes.

US District Judge Jesse Furman in Manhattan said Commerce Secretary Wilbur Ross concealed his true motives in adding the question last March. Ross had said the question -- which has not appeared on the decennial census since 1950 -- was necessary to enforce federal laws protecting eligible voters.

But Furman said Ross and his aides behaved "like people with something to hide," leading to the "inescapable" conclusion that they "did have something to hide."

Furman's decision will almost certainly be appealed and could wind up before the Supreme Court this year.

The plaintiffs -- 18 US states, 15 cities and various civil rights groups -- said that asking census respondents whether they are US citizens will frighten immigrants and Latinos into abstaining from the count.

That could cost their mostly Democratic-leaning communities representation in the US House of Representatives, as well as their share of some $800 billion a year in federal funding.

The plaintiffs alleged that was Ross' plan all along, while he insisted the government needed citizenship data to better enforce the Voting Rights Act, which protects eligible voters from discrimination. Only American citizens can vote in federal elections.

Dale Ho, an attorney with the American Civil Liberties Union who argued the plaintiffs' case, called Furman's ruling "a forceful rebuke of the Trump administration's attempt to weaponize the census."

Kelly Laco, a Justice Department spokeswoman, said the administration was "disappointed," adding that the "government is legally entitled to include a citizenship question on the census, and people in the United States have a legal obligation to answer."

In a 277-page opinion, Furman called Ross' Voting Rights Act rationale "pretextual."

"He announced his decision in a manner that concealed its true basis rather than explaining it," Furman said.

Ross said he added the question at the request of the Justice Department, but evidence at trial showed he independently pushed for it much earlier.

Ross also chose not to heed recommendations from experts - including from within the Census Bureau itself -- who said adding the question would lead to an undercount and hurt data quality.

During a two-week trial in November, Justice Department lawyers argued Ross need not reveal every motivating factor, as long as his stated rationale was sound.

They also said he was under no obligation to take advice from experts. Ross "doesn't have to choose the best option" as long as he considers all evidence in good faith, Justice Department lawyer Brett Shumate said at trial.

Reuters