A lawsuit challenging the Trump administration's decision to ask people about their citizenship status during the 2020 Census can move forward, a New York federal judge ruled Thursday. 

U.S. District Court Judge Jesse Furman found that the U.S. Census Bureau has the right to ask about citizenship. But he will continue the lawsuit because plaintiffs "plausibly allege" that Commerce Secretary Wilbur Ross' decision to add the question stemmed from "discriminatory animus and that its application will result in a discriminatory effect."

But Furman cautioned that plaintiffs might not ultimately be victorious, underscoring that Ross has "broad authority" over the census.

A group of 17 states, along with advocacy organizations and cities, filed the lawsuit earlier this year, arguing that the decision to ask census respondents about whether they are legal citizens would "drive down response rates" and therefore result in a census that doesn't accurately reflect the population.

The concern is that non-citizens will not participate in the census because they are afraid it will result in an enforcement action by immigration authorities, which would then result in undercounting of the number of people living in certain places. This could lead to locations with high numbers of undocumented immigrants losing out on federal grant dollars, while also potentially leading to certain states or cities being penalized when congressional boundaries are drawn based on population. 

The Census Bureau and Commerce Department have retorted in court filings that there is "little 'definitive, empirical' evidence" about the effects of asking about citizenship, while saying the bureau has procedures for getting information about households that don't respond. 

The bureau eliminated the citizenship question entirely in 2010 and hasn't used it with all census respondents since 1950. In his opinion, Furman noted that Census Bureau officials in recent counts—which under the U.S. Constitution must take place every decade—have opposed efforts to reinstate it across-the-board, warning it will result in inaccurate count. 

Earlier this week, The New York Times reported that emails filed in the court record as part of the lawsuit showed Trump administration officials from the very beginning of the president's time in office urging Commerce officials to move on the issue of including a citizenship question. The article noted these emails undermined the Commerce Department's contention in the lawsuit that they acted at the request of the Justice Department, which said the information was necessary for Voting Rights Act enforcement.

But a Commerce spokesman responded to the Times that the documents filed as part of the case merely show the good government practice of officials discussing issues before making policy changes. 

After Furman's opinion, an agency spokesman said Commerce officials were pleased that the judge recognized Ross' "broad authority" to deal with the census. "We are confident that this includes the authority to reinstate a citizenship question and that plaintiffs’ remaining claims will be dismissed after discovery shows that the secretary lawfully exercised his discretion to do so," he said in an email.

But New York Attorney General Barbara Underwood countered in a statement that the opinion allowing the case to proceed is a "big win."

"As we’ve argued, the Trump administration’s plan to demand citizenship status as part of the Census is unlawful—and it would potentially cause a huge undercount that would threaten billions in federal funds and New York’s fair representation in Congress and the Electoral College," she said.  

Not all states are opposed to the inclusion of a question about a person's citizenship status. The state of Alabama has filed its own lawsuit against the bureau to block counting people without legal documentation. The state argues it could potentially lose a congressional representative if undocumented residents in other states are counted.