The Role of Penal Quarantine in Reducing Violent Crime
Authors: Johnson Perry M. 
Published: March 2007

In reviewing the aims and functions of imprisonment, the author argues that protection of the public should be the basis for decisions regarding incarceration. Quarantine, or isolation, is presented as an incarcerative function that is particularly susceptible to rational analysis as to its impact on public protection. An examination of the limits of quarantine's poten tial effect under actual and ideal circumstances leads to the conclusion that current proposals for increasing the use of quarantine would reduce seri ous violent crime by no more than 10 percent, at a staggering cost for prison construction and operation. Two alternative proposals are then presented. The first is a system of selective quarantine, based on a person's potential for future violence, which could be implemented within the current jurisdictional authority of the correctional system. The second proposal expands on the correctional model by adding changes within the authority of the judicial system. This second model is found to be most effective in reducing crime, and a cost- benefit analysis shows that its cost efficiency is nearly twice that of the existing system, and several times better than some competing proposals. 1. J. D. Mabbott, "Punishment," in Theories of Punishment, Stanley E. Grupp, ed. (Bloom ington : Indiana University Press, 1971), p. 41. 2. Paul W. Tappan, Crime, Justice and Correction (New York: McGraw-Hill, 1960), p. 242. 3. Cesare Beccaria, "On Crimes and Punishments," in Theories of Punishment, pp. 125-26. 4. Norval Morris and Franklin Zimring, "Deterrence and Corrections," Annals of the Ameri can Academy of Political and Social Science, January 1969, pp. 137-46. 5. Daniel Glaser, The Effectiveness of a Prison and Parole System (New York: Bobbs-Merrill, 1964), p. 13. 6. Ibid., p. 16. 7. Norval Morris and Gordon Hawkins, The Honest Politician's Guide to Crime Control (Chicago: University of Chicago Press, 1970), p. 118. 8. Norval Morris, The Future of Imprisonment (Chicago: University of Chicago Press, 1974), p. 73. 9. James Q. Wilson, Thinking about Crime (New York: Basic Books, 1975), p. 201. 10. New York Times, Mar. 9, 1975, sec. 6, p. 4. 11. Stephan Van Dine, Simon Dinitz, and John Conrad, "The Incapacitation of the Dangerous Offender: A Statistical Experiment," Journal of Research in Crime and Delinquency, January 1977, p. 34. 12. The term repeater is restricted to an adult offender who has been convicted of any felony (not restricted to violent crimes) who subsequently commits a violent crime that is also a felony. The FBI Index of Reported Crime classifies homicide, forcible rape, robbery, and aggravated assault as violent crimes, excluding burglary, larceny of more than $50, and auto theft-the re maining three "serious crimes." Since Michigan state police report crime by FBI categories, these four violent felonies are the reported crimes referred to in this paper. Convictions are based on the Michigan penal code. 13. Uniform Crime Report, State of Michigan, 1975, p. 22. Nineteen percent of arrests for murder, nonnegligent homicide, rape, robbery, and aggravated assault were juveniles. A Michi gan Department of Corrections computer run, April 2, 1975, established that 15 percent of per sons convicted for violence had a prison record. Since two of three felony convictions normally result in a nonprison disposition and these offenders are only one-half as likely to repeat, I assume that the proportion of persons convicted of a violent crime having committed a felony but not sentenced to prison would be no more than 15 percent. Thus, 30 percent (15 percent + 15 percent) appears to be a conservative estimate of the proportion of convictions for violent crime represented by repeaters. 14. Cited in Van Dine, Dinitz, and Conrad, "Incapacitation of the Dangerous Offender," p. 23. 15. Dimensions, Michigan Department of Corrections Annual Report, 1975. 16. Ibid., p. 13. 17. Ibid. 18. Ibid., p. 114. 19. Ibid., pp. 112, 114. 20. Morris, Future of Imprisonment, p. 73. 21. William Kime, "Early Findings-Risk of Violent Behavior on Parole," unpublished (Michi gan Department of Corrections, June 10, 1976), pp. 1-5. The risk study referred to was based on a 50 percent sample of all 1971 parolees from the Michigan prison system. The total sample was just over 2,000 cases. Each case was coded on some 350 variables, including factors related to parole outcome. Multivariate analysis (automatic interaction detection) was used to identify cor relates of both assaultive and nonassaultive crime committed on parole. Half the sample was used to construct the predictors; the other half was reserved for validation. Thus, the predictors and risk categories referred to in this analysis have been validated. The detailed findings of the study have not been used here, but a generalized example based on these study results is employed for purposes of simplicity. Those interested in a more detailed explanation of the study methodology and findings may obtain this by writing the Michigan Department of Corrections. 22. Ibid., pp. 5-6. 23. Under the criteria for categories identified in the risk study and used for this example, no property offender can be high risk, and no violent offender can be low risk. 24. Compiled from Michigan Department of Corrections, Criminal Statistics, 1971-75. The figures combine probation, jail, fines, and other nonprison dispositions for felony convictions.