After two weeks of reversals and uncertainty, there won’t be a question about citizenship on the 2020 census after all. This is a victory for opponents of the question, as social scientists and civil rights advocates had argued that it would deter immigrants and their families from responding to the census and lead to an inaccurate count. But this doesn’t mean that the Trump administration has abandoned its plan to collect data on people’s citizenship status.

On Thursday, Trump issued an executive order requiring that federal agencies turn over all the information they have on people’s citizenship and immigration status to the Census Bureau. Trump also doubled down on what many suspected was one of his administration’s goals — making the data available for redistricting. Experts I talked to said it’s very likely that if Trump’s efforts are successful, at least some state legislators will try to use the citizenship data when new electoral maps are drawn in 2021, which could further entrench Republican power in the states and kick off a whole new legal battle.

Currently, states draw electoral maps based on total population, including people who aren’t eligible to vote. But when the Trump administration announced in March 2018 that it was adding the citizenship question to the census, it seemed likely that if detailed data about citizenship became available, legislators in some states would draw their maps based on the number of citizens or eligible voters. Trump alluded to this move in his Thursday announcement, saying, “Some states may want to draw state and local legislative districts, based upon the voter-eligible population.” And as I wrote last month, this likely would benefit Republicans by shifting political power away from diverse urban areas and toward rural parts of their state.

If this were to happen, it would certainly send the states into uncharted legal waters. The Supreme Court ruled decades ago that the distribution of congressional seats must be based on total population, but it has yet to rule on whether states are allowed to base their maps on the number of citizens, or what kind of data they could use to do it. So if state legislators do take the new data and run with it, the Trump administration could still kick off a legal showdown about who counts for the purposes of political representation.

In theory, the data actually could solve a practical problem that emerged during a 2016 Supreme Court case that argued that states should only draw electoral maps based on eligible voters. There wasn’t block-level citizenship data available for the intricate process of drawing district lines. The court ultimately rejected the idea that redistricting using eligible voters should be mandatory but sidestepped whether states could do it voluntarily (and what data they’d need to use), leaving the door open for a future case.

And the data now being compiled by the Trump administration might be granular enough to be used for redistricting. It’s not clear, though, whether the data will be good enough to survive a legal challenge if it ends up forming the basis of electoral maps. In 2018, Census Bureau researchers wrote that they would need to use statistical modeling to assign citizenship status to the people who aren’t covered by administrative records, which they estimated would be about 10 percent of the population. And other data quality concerns could be raised as well. For one thing, some of the federal records data could be out of date. And connecting citizenship status to names and addresses will be complicated. “Matching all of this information across federal databases is not necessarily as easy as it sounds,” said Michael Li, senior counsel at the Brennan Center for Justice. “There are some concerns about mismatches — think about all the people who have the same name and live in the same area. A court will have to accept that this is a valid methodology that produces valid results.”

And the fact that the data doesn’t come from the census could be a roadblock in some states. According to a study by the National Conference of State Legislatures, 21 states have explicit provisions saying that only data from the decennial census can be used for drawing legislative districts.

Then, if a state tries to redistrict using citizenship data, the Supreme Court will almost certainly have to address the deeper question of whether people who can’t vote — including, in some proposals, citizens under the age of 18 — can be excluded for the purposes of political representation. This dispute is, fundamentally, about what the principle of “one person, one vote” really means. Proponents of changing how redistricting is done have argued that because electoral districts have to have roughly the same number of people in them, only voters should count — otherwise the votes of people in districts with lots of ineligible voters have more political power. Others who want to continue basing electoral districts on the total population of an area have pointed out that those who can’t vote still pay taxes and use public services, which means they still have a stake in what politicians do.

But convincing the Supreme Court that congressional districts can be drawn using something other than total population will be a long shot, according to Justin Levitt, a professor at Loyola Law School in Los Angeles, because the justices have been explicit that congressional seats have to be distributed among the states using total population. The court hasn’t explicitly addressed how that process has to happen within the state, but Levitt thinks it will be hard to argue for a different denominator. “It doesn’t make sense, as a legal principle, to count everyone for the purpose of assigning the seats to the states but then say you don’t have to count everyone when you’re determining where they go,” he said.

But there’s a lot more ambiguity about state and local districts — and advocates may decide to test the Supreme Court’s position on congressional maps as well. After all, there’s potentially a big reward for Republicans if they’re successful, since researchers have predicted that redistricting using only citizens or eligible voters could increase the number of GOP-dominated districts.

Of course, all of these battles are still in the distance, and whether they will be fought at all depends, to some extent, on the winner of the 2020 presidential election. If a Democrat takes over the White House in 2021, his or her administration could block the use of this citizenship data. But if Trump is still in office, his administration’s efforts to gather more detailed data seem likely to bring the debate over citizenship and political power right back to the Supreme Court.