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.

DOJ alleges that since at least 2012, more than a quarter of the people due to be released from Louisiana prisons have instead been held past their release dates. DOJ warned Louisiana officials last year that the state could face a lawsuit if it didn’t fix the problems, but lawyers for the department say the state’s “marginal efforts” to address the issues were “inadequate” and showed a “deliberate indifference” to the constitutional rights of incarcerated individuals.

In a joint statement provided to The Associated Press, Louisiana Gov. Jeff Landry and state Attorney General Liz Murrill blamed the problem on the “failed criminal justice reforms” advanced by “the past administration.”

— The Associated Press