The National Security Agency admitted in documents released Tuesday that it had wrongly put 16,000 phone numbers on an “alert list” so their incoming calls could be monitored, a mistake that a judge on the secret surveillance court called a “flagrant violation” of the law, the Los Angeles Times reports.

The Electronic Frontier Foundation and the American Civil Liberties Union sued and sought the documents under the Freedom of Information Act.

They “showed that the NSA repeatedly violated court-imposed limits on its surveillance powers, and they confirm that the agency simply cannot be trusted with such sweeping authority,” ACLU attorney Alex Abdo said.