The Justice Department hast sued the state of Louisiana for unlawfully imprisoning thousands of people for weeks after their sentences concluded.

Louisiana’s prison system routinely holds people weeks and months after they have completed their sentences, the U.S. Department of Justice alleged in a lawsuit filed Friday. The suit against the state of Louisiana follows a multiyear investigation into what federal officials say is a pattern of “systemic overdetention” that violates inmates’ rights and costs taxpayers millions of dollars a year.