The ruling marks the opening round in a legal battle with potentially profound ramifications for federal policy and for politics at all levels, one that seems certain to reach the Supreme Court before the printing of census forms begins this summer.
A broad coalition of advocacy groups and state and local officials had argued that the citizenship question was effectively forced into the census under false pretenses, in violation of laws enacted to ensure that federal policies heed the public interest.
At first blush, the central question of the lawsuit — whether the 2020 census should ask respondents if they are citizens — seems mundane enough. A similar question was asked in most federal censuses before 1960, and it is still asked by the Census Bureau in the American Community Survey, which samples about 2.6 percent of the population each year.
But opponents argued that adding the question to the census itself would undermine the constitutional mandate to count every person, regardless of citizenship, because it would discourage noncitizens from filling out the questionnaire for fear of persecution. That was especially true, they said, in light of the Trump administration’s open hostility toward some immigrant groups and its campaign to round up and deport undocumented residents.
Roughly 24 million noncitizens live in the United States, and fewer than 11 million of them do so illegally. Nearly 1 in 10 households includes at least one noncitizen. A substantial reduction in the number of households that respond to the census could alter the distribution of hundreds of billions of dollars in federal grants and subsidies.
Total population figures will be used to reapportion seats in the House of Representatives in 2021, so the contours of Congress, the Electoral College and thousands of state and local political districts could be affected. Because noncitizens tend to live in places that disproportionately vote Democratic, undercounting them in the census would be likely to shift federal spending and political power to Republican areas.
This article originally appeared in The New York Times.