In an arti­cle enti­tled The Death Penalty: No Evidence for Deterrence, John Donnohue and Justin Wolfers exam­ined recent sta­tis­ti­cal stud­ies that claimed to show a deter­rent effect from the death penal­ty. The authors con­clude that the esti­mates claim­ing that the death penal­ty saves numer­ous lives ​“are sim­ply not cred­i­ble.” In fact, the authors state that using the same data and prop­er method­ol­o­gy could lead to the exact oppo­site con­clu­sion: that is, that the death penal­ty actu­al­ly increas­es the num­ber of mur­ders. The authors state: ​“We show that with the most minor tweak­ing of the [research] instru­ments, one can get esti­mates rang­ing from 429 lives saved per exe­cu­tion to 86 lives lost. These num­bers are out­side the bounds of credibility.”

The authors con­clude that the evi­dence of deter­rence is far too weak to rely on as a jus­ti­fi­ca­tion for the death penalty:

The view that the death penal­ty deters is still the prod­uct of belief, not evi­dence. The rea­son for this is sim­ple: over the past half cen­tu­ry the U.S. has not exper­i­ment­ed enough with cap­i­tal pun­ish­ment pol­i­cy to per­mit strong con­clu­sions. Even com­plex econo­met­rics can­not side­step this basic fact. The data are sim­ply too noisy, and the con­clu­sions from any study are too frag­ile. On bal­ance, the evi­dence sug­gests that the death penal­ty may increase the mur­der rate although it remains pos­si­ble that the death penal­ty may decrease it. If cap­i­tal pun­ish­ment does decrease the mur­der rate, any decrease is likely small.

John Donohue is a pro­fes­sor at Yale Law School and a Research Associate at the National Bureau of Economic Research. Justin Wolfers is a pro­fes­sor at the Wharton School of Business and a Research Affiliate at the National Bureau of Economic Research. (The Economists’ Voice, April 2006). Read the arti­cle. See Deterrence and Studies.

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