California's 1994 "Three Strikes and You're Out" legislation is one of the most controversial pieces of crime control legislation in American history and one of the most important as well. The California law has produced nine times as many mandatory prison sentences as the other 25 three strikes states and the federal government combined. Because the law came into effect during a period of declining crime rates, it has been widely assumed that three strikes has been responsible for a major share of California's crime decline, but no rigorous evaluation of the impact of the law has been reported until this study.

This monograph reports an analysis of thousands of arrests before and after the California statute went into effect in three cities—Los Angeles, San Diego and San Francisco. The study shows that one in 10 felony arrests involves a defendant with either one or two prior strike convictions. More surprising those who are eligible for the new law's increased penalties did not decline as a percentage of those arrested in the first two years after the new legislation. Since 90 percent of California criminals were not covered by three strikes, the potential impact of the law on crime rates was modest. Since the arrest rate among persons not subject to the new penalties dropped as much as the arrest rate for the targets of three strikes, the legislation does not appear to be an important part of the general decline in California crime.