Prison leaders wrote a bill to release prisoners earlier.

In 2011, the Nebraska Department of Correctional Services wrote a bill that would allow well-behaved prisoners the chance to shorten their time behind bars.

Eleven years later, that same department is applying the resulting law in a way neither the state senator who sponsored the bill nor the then-director of Nebraska’s prisons intended.

Prison officials now shorten a prisoner’s final release date, but never change the day that prisoner becomes eligible for parole.

The result: Thousands of prisoners sentenced under the law have potentially stayed in prison days, weeks or months longer than the...