After months of preparation—and despite plenty of pushback—Department of Commerce Secretary Wilbur Ross announced Monday night that the 2020 Census will include a question about respondents’ immigration status. State attorneys general and immigration and civil-rights groups were quick to slam the move and, within hours of the announcement, California Attorney General Xavier Becerra filed a lawsuit challenging the decision.

The move will have profound consequences for US democracy. The Census, which happens only once every 10 years, is used to determine the allocation of $700 billion in federal grant money, apportion representatives in Congress, and determine how electoral boundaries are drawn and how many votes each state is given in the Electoral College. Critics have long warned that a question about people’s immigration status will depress participation and lead to inaccurate responses, both of which could warp the administration of these immensely consequential programs and institutions.

Still, Ross determined, the question is necessary for the enforcement of the Voting Rights Act. “The reinstatement of a citizenship question will not decrease the response rate of residents who already declined not to respond,” Ross wrote in a memo released Monday, brushing off concerns about lower participation. “And no one provided evidence that there are residents who would respond accurately to a decennial census that did not contain a citizenship question but would not respond if it did.”

Becerra and California Secretary of State Alex Padilla wrote in an op-ed Monday that Ross is not just wrong but that the query is unconstitutional: “Including a citizenship question on the 2020 census is not just a bad idea—it is illegal. The Constitution requires the government to conduct an ‘actual enumeration’ of the total population, regardless of citizenship status.” This question, Becerra and Padilla warned, will do the opposite.

It’s not just crusading Democrats who are concerned. Multiple previous directors of the Census Bureau have warned against adding a question about immigration status back to the Census. “It will drive the response rate down enormously,” Kenneth Prewitt, a former director of the Census Bureau and now a professor at Columbia, told The Washington Post. “If you drive those people out of the Census, the consequence is that they’re not in it. It’s a step toward not counting the people you don’t want to count. And that goes very far in redrawing legislative boundaries.”

As early as September of last year, months before the announcement that the question was a possibility, Census researchers spoke up about exactly these concerns. “[Center for Survey Measurement] researchers have noticed a recent increase in respondents spontaneously expressing concerns about confidentiality in some of our pretesting studies conducted in 2017.” Researchers said respondents had specific fears about sharing confidential information with researchers, and attributed it to moves from the Trump administration to target immigrants and people of color, such as the Muslim travel ban, the dismantling of DACA, and the empowerment of ICE agents.

Respondents, researchers found, were uncomfortable “registering” and possibly endangering other household members by answering questions, and sometimes even made up inaccurate responses.

And as it is, the Census Bureau itself estimated that its 2010 count undercounted the Latino population in the United States by 1.5 percent and the black population by 2.1 percent, numbers that experts say will be much worse with the new question.

The Trump administration is the embodiment of reactionary white anxiety about the country’s changing demographics, and this one simple question, “Are you a citizen?” is another swipe at the power and presence of people of color. But this decision, unlike bad or illegal policy, can’t be repealed or dismantled. The Census is a one-time event, and the consequences of it will be felt long after Trump leaves office.