As a matter of fact, both the incarceration rate and the crime rate in the United States vary a great deal from one state to another. About 25 or 30 states—I do not know the exact number—use “three strikes laws”, but there is no relationship between that use and the fact that the crime rate has decreased or not. In the United States as in Canada, moreover, crime rates have decreased considerably since 1990-1991, but the decrease is not at all linked to the “three strikes” or to incarceration. That is a very important fact.
A very enlightening comparison can be made. In United States, violent and non violent crime rates have decreased significantly since 1990. The same is true in Canada. Studies have showed that the decrease followed the same curve, in other words, the percentage was more less the same. However, in the United States from 1970 to date, the incarceration rate has gone from 215 to 750, which is not the case in Canada, where the incarceration rate remained quite stable over that period. It varied only from 10 to 15 out of every 100,000 inhabitants. Consequently, incarceration cannot, generally speaking, be considered responsible for reducing crime rates in United States. In fact, Canada experienced the same type of decrease without an increase in the incarceration rate.