The Supreme Court permitted the Trump administration to expand a federal database containing citizenship information, as the president encourages states to purge people from voter rolls.

Critics have said the data is unreliable and could lead to U.S. citizens being kicked off the voter rolls. But the court noted in its unsigned ruling that the National Voter Registration Act bars the broad purging of voter rolls in the weeks leading up to an election, which “limits the potential impact” of the decision.