HARRISBURG, Pa.—Gov. Tom Corbett has signed legislation that gives Pennsylvania judges options other than life in prison when sentencing juveniles in murder cases.

The law signed Thursday by Corbett means defendants 14 or younger would serve at least 20 years for second-degree convictions and 25 years for first-degree convictions. Offenders who are 15- to 17-years old would face at least 25 or 35 years.

The measure was spurred by the U.S. Supreme Court's decision that recently outlawed mandatory life-without-parole terms for minors, deeming it cruel and unusual punishment.

The Pennsylvania legislation creates a new set of sentencing options, with penalties that depend on the age of the defendant and whether they're convicted of first- or second-degree murder.

Pennsylvania prison officials have estimated the number of juvenile lifers at about 300.