A voter purge by Florida’s Secretary of State Ken Detzner in 2012 violated the law, a federal appeals court ruled in the most recent episode of a heated legal battle over the program and its possible successor.

The 11th U.S. Circuit Court of Appeals rejected arguments from Detzner that the effort to remove suspected non-citizens from the voting rolls did not violate a federal law barring wide-ranging efforts to cleanse those rolls within 90 days of an election. In the 2-1 ruling, justices also said they took a case that would otherwise be moot because of the possibility that the state will attempt another purge in the future.