Three-strikes laws impose sharply enhanced sentences — often 25 years to life — on defendants convicted of a third qualifying felony. The federal government and roughly half of states have some version. California's was the most expansive and best-known; voters narrowed it in 2012 to require the third strike to be a serious or violent felony.
Supporters argue the laws incapacitate the small share of offenders responsible for a large share of serious crime, and deter repeat offending. Critics argue the laws have produced grossly disproportionate sentences (e.g., life sentences for low-level third offenses), driven prison populations and costs sharply upward, and produced little measurable deterrent effect.
Reform efforts have generally narrowed which prior convictions count, restricted the third strike to serious or violent offenses, or added judicial discretion to depart from mandatory sentences.