California's Three Strikes sentencing law was originally enacted in 1994. The essence of the Three Strikes law was to require a defendant convicted of any new felony, having suffered one prior conviction of a serious felony to be sentenced to state prison for twice the term otherwise provided for the crime. If the defendant was convicted of any felony with two or more prior strikes, the law mandated a state prison term of at least 25 years to life.

On November 6, 2012 the voters approved Proposition 36 which substantially amended the law with two primary provisions:

1. the requirements for sentencing a defendant as a third strike offender were changed to 25 years to life by requiring the new felony to be a serious or violent felony with two or more prior strikes to qualify for the 25 year-to-life sentence as a third strike offender; and
2. the addition of a means by which designated defendants currently serving a third strike sentence may petition the court for reduction of their term to a second strike sentence, if they would have been eligible for second strike sentencing under the new law.

Resources:

Video: Prop 36 Amendments to California's Three-Strikes Sentencing

Playlist Index: Part 1: Introduction Part 2: Use of a Firearm Part 3: Prior Offenses Part 4: Consecutive Sentencing Part 5: Petitioning for Resentencing Part 6: Multiple Counts Part 7: Qualification Hearing Part 8: Court's Discretion Part 9: Pleadings and Retrial Part 10: Order of the Court view the full video (54:57)

The Amendment of the Three Strikes Sentencing Law (January 2013) by J. Richard Couzens, Judge of the Superior Court of Placer County(Ret.) and Presiding Justice Tricia A. Bigelow, Court of Appeal, 2nd Appellate District, Div. 8