Nebraska has joined 15 other states in filing a motion with the U.S. Supreme Court in a case that could affect hundreds of death-row inmates nationwide.
The states files the brief after the high court agreed to clear up confusion over the impact of one of its 2002 rulings.
That ruling said that juries, not judges, must have the final say in who gets the death penalty.
The justices agreed to decide whether inmates already on death row can use the ruling to argue that they deserve a lesser punishment.
The ruling forced changes in the death penalty laws in Nebraska and several other states.
Attorney General Jon Bruning said, "The implications of retroactivity are staggering."
The brief was written by Nebraska Solicitor General J Kirk Brown.