Truth-in-sentencing, law enforcement, and inmate population growth

This paper presents the empirical estimation of an econometric model of the flow of prisoners into a state correctional system. Specifically, an econometric model was built to control for the number of parolees, the probability of admission to the state system, the size of the state population, the unemployment and poverty rates, the number of law enforcement officers within the state, and the state-wide “truth-in-sentencing” law, which requires convicts to serve at least 85% of their sentences. One primary result was that increases in the number of law enforcement officers has generated a decline in the growth rate of the prison population. This suggests that a “deterrent effect” is created when more police are placed on the beat. Furthermore, the results indicate that the truth-in-sentencing law has also slowed the rate of inmate population growth. This finding may reflect the growing trend for courts to hand down nontraditional sentences and to adjust prison sentences to reflect a constant “real time” of incarceration by crime.