In a recent arti­cle in the Ohio State Journal of Criminal Law, Dr. Jeffrey Fagan of Columbia University describes numer­ous seri­ous errors in recent deter­rence stud­ies, includ­ing improp­er sta­tis­ti­cal analy­ses and miss­ing data and vari­ables that are nec­es­sary to give a full pic­ture of the crim­i­nal jus­tice sys­tem. Fagan writes, ​“There is no reli­able, sci­en­tif­i­cal­ly sound evi­dence that [shows that exe­cu­tions] can exert a deter­rent effect…. These flaws and omis­sions in a body of sci­en­tif­ic evi­dence ren­der it unre­li­able as a basis for law or pol­i­cy that gen­er­ate life-and-death deci­sions. To accept it uncrit­i­cal­ly invites errors that have the most severe human costs.”

Since the land­mark Supreme Court deci­sion in Furman v. Georgia in 1972, dozens of stud­ies have been per­formed to deter­mine whether future mur­der­ers are deterred by the death penal­ty. In the past five years, Fagan writes, a ​“new wave” of stud­ies has emerged, claim­ing that each exe­cu­tion pre­vents 3 – 32 mur­ders, depend­ing on the study. Some of these stud­ies tie par­dons, com­mu­ta­tions, exon­er­a­tions, and even irra­tional mur­ders of pas­sion to increas­es in murder rates. 

While many of these stud­ies have appeared in aca­d­e­m­ic jour­nals, they have been giv­en an uncrit­i­cal and favor­able recep­tion in lead­ing news­pa­pers. Fagan takes issue with this lack of seri­ous and ade­quate peer review by fel­low researchers. He ana­lyzed this research and found that ​“this work fails the tests of rig­or­ous repli­ca­tion and robust­ness analy­sis that are the hall­marks of good sci­ence.” His arti­cle details the flaws in these stud­ies, including:

  • inap­pro­pri­ate meth­ods of statistical analysis
  • fail­ures to con­sid­er sev­er­al rel­e­vant fac­tors that dri­ve mur­der rates such as drug epidemics
  • miss­ing data on key vari­ables in key states
  • sta­tis­ti­cal con­found­ing of mur­der rates with death sentences
  • fail­ure to con­sid­er the effect of the gen­er­al per­for­mance of the crim­i­nal jus­tice sys­tem on the murder rate.

(Death and Deterrence Redux: Science, Law and Causal Reasoning on Capital Punishment by Jeffrey Fagan, 4 Ohio State Journal of Criminal Law 255 (2006)). See also Deterrence and Resources.

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