Twenty-eight states have some form of a "three-strikes" law.
In general, most people agree that a young child should not be treated the same as adults when it comes to punishment or legal accountability. Since young children are still developing an understanding of social and ethical norms, the law usually does not hold young children accountable for their actions -- that is, young children lack something called “legal capacity.” While the law cannot assign legal responsibility to an individual who lacks the mental capacity or maturity to understand the consequences of his or her actions, at what point does someone legally become an adult?
People certainly mature at different ages, but states must draw the line somewhere.
But such sentences were not compulsory in each case, and judges had much more discretion as to what term of incarceration should be imposed.
The first true "three-strikes" law was passed in 1993, when Washington voters approved Initiative 593.
The following chart provides a quick summary of California's legal age laws.