The Supreme Court has rejected a challenge to President Trump’s plan to exclude illegal immigrants from the count used to allocate seats in congress to states based on population.

The constitution requires only that there be a count of “the whole number of persons” in the United States every 10 years.

According to NPR:

The U.S. Supreme Court dodged a ruling on whether President Trump can exclude undocumented immigrants from a key census count. The opinion said the case was “riddled with contingencies and speculation that impede judicial review.”

“At the end of the day, the standing and ripeness inquiries both lead to the conclusion that judicial resolution of this” case is “premature,” the justices wrote.

The decision leaves open the possibility for Trump to try to remove some undocumented immigrants from a key census count, but immigrant rights advocates warned Friday that they would sue.

“If the Administration actually tries to implement this policy, we’ll sue. Again. And we’ll win,” Dale Ho, director of the American Civil Liberties Union’s voting rights project, said on Twitter.

President Trump issued an executive memorandum in July directing the Census Bureau to send him two sets of numbers. One containing the whole number of persons and the other showing the population when illegal immigrants were subtracted.