WASHINGTON — A decision by the Trump administration to add a question on citizenship to the 2020 census discriminates against ethnic minorities for political gain, violating the Constitution, argues a federal lawsuit brought Thursday on behalf of several groups representing minorities.
The lawsuit, filed by 21 organizations and two citizen plaintiffs in United States District Court in Maryland, is the fourth major effort to block a citizenship question from the 2020 tally. The first suit, filed in April by a mostly Democratic coalition of state attorneys general and cities, argued that the citizenship question violated the Constitution’s requirement that a census count everyone residing in the United States, as well as laws governing data quality and administrative procedure.
The latest suit repeats those claims, but also argues that the administration added the question to deter Asian-Americans, Latinos and some immigrants from completing census forms for fear that the information would be used against them or members of their household, and thus undercount them in the final census tally. A serious population undercount, the plaintiffs said, would reduce minority representation in the House of Representatives and state and local governments when political districts are reapportioned early next decade.
That violates the Fifth Amendment’s equal-protection clause, the lawsuit states — the first time that opponents of the citizenship question have leveled a charge of intentional discrimination against the administration for its census decision.
Both Asian-Americans and Latino voters tend to favor Democratic candidates, and political scientists and strategists universally agree that undercounting their true share of the population likely would increase Republican political control.
By adding a citizenship question to the tally, administration officials “believe reducing the Latino count would hurt in reapportioning states that they have a political interest in hurting,” said Thomas A. Saenz, the president and general counsel of the Mexican American Legal Defense and Educational Fund, which represents the plaintiffs. “I’m not sure that’s entirely correct, but I think that’s what is behind it.”
More than that, Mr. Saenz said, the decision to add a citizenship question fits a pattern of attacks on the legitimacy of Latinos and other minorities that dates to the start of Donald J. Trump’s presidential campaign.
Mr. Trump began his presidential bid in June 2015 by calling undocumented Mexican immigrants “rapists” who brought drug and crime problems with them. Rhetorical assaults on immigrants have become a staple of his political appearances, and efforts to restrict legal immigration and deport undocumented residents are major policy goals.
The lawsuit devotes almost eight pages to past statements on immigration and immigrants by Mr. Trump, during his candidacy and presidency, and by administration officials as evidence of the administration’s intent to single out foreigners as a threat.
Representatives for the United States Census Bureau, the Commerce Department and the White House did not immediately respond to a request to comment.
The Census Bureau does ask a small slice of the population about citizenship in a poll, the American Community Survey, which provides periodic snapshots of demographic changes for civic and business leaders.
But no general census has asked respondents to state their citizenship since 1950. In recent decades, the Census Bureau had fought repeatedly to block the question, and in 2009, eight former directors of the bureau warned Congress that it “would put the accuracy of the enumeration at risk,” because noncitizens and their relatives would either refuse to fill out the form or lie about their status.
Inside the bureau, experts warned as recently as last year of “unprecedented” concern among minorities who were asked to respond to test census forms that the Trump administration would seize on legally confidential census information to target them or their household members for harassment or deportation. In meetings with census workers, even some legal immigrants gave false responses on test census forms or refused to provide information on roommates or family members.
Then the Justice Department said that it needed more information on citizenship to enforce the 1965 Voting Rights Act. In late March, Commerce Secretary Wilbur L. Ross Jr. ordered that the citizenship question in the American Community Survey be added to the 2020 census.
Mr. Ross wrote then that the question had been used in that survey without incident, and that there was no “definitive, empirical support” for concerns that it would deter minorities from filling out census forms.
But demographers and other census experts, including the bureau’s own Scientific Advisory Committee, dispute that. Civil-rights advocates and some former Justice Department lawyers have said that the Voting Rights Act has been enforced for decades with existing citizenship data, and that the demand for more was but a pretext for adding the question to the decennial census.