“Three Strikes and You're Out”: The Impact of California's New Mandatory Sentencing Law on Serious Crime Rates

Using monthly data drawn from the 10 largest cities in California and an interrupted time-series design with nonequivalent dependent variables, the authors assessed the impact of California's “three strikes and you're out” law on the serious crime rate and on a control series measured as the petty theft rate. Overall, maximum-likelihood results indicated that the three-strikes law did not decrease serious crime or petty theft rates below the level expected on the basis of preexisting trends. Policy implications of these findings are discussed, and explanations are given as to why the effect of California's three-strikes law was inconsequential in 9 of the 10 cities examined.