NCPA - National Center for Policy Analysis


November 2, 2007

Most commentators who oppose capital punishment assert that an execution has no deterrent effect on future crimes.  Recent evidence, however, suggests that each execution carried out is correlated with about 74 fewer murders the following year, say Roy D. Adler, a professor of marketing and Michael Summers, a professor of quantitative methods at Pepperdine University.

Their study examined the relationship between the number of executions and the number of murders in the United States for the 26-year period from 1979 to 2004, using data from publicly available FBI sources.  There seems to be an obvious negative correlation in that when executions increase, murders decrease, and when executions decrease, murders increase.

  • In the early 1980s, the return of the death penalty was associated with a drop in the number of murders. In the mid-to-late 1980s, when the number of executions stabilized at about 20 per year, the number of murders increased.
  • Throughout the 1990s, our society increased the number of executions, and the number of murders plummeted.
  • Since 2001, there has been a decline in executions and an increase in murders.

The conclusion that each execution carried out is associated with the saving of dozens of innocent lives creates an extraordinarily difficult moral dilemma for those who campaign against the death penalty.  It now seems that the proper question to ask goes far beyond the obvious one of "do we save the life of this convicted criminal?"  The more proper question seems to be "do we save this particular life, at a cost of the lives of dozens of future murder victims?"  That is a much more difficult moral dilemma, which deserves wide discussion in a free society, say Adler and Summers.

Source: Roy D. Adler and Michael Summers, "Capital Punishment Works," Wall Street Journal, November 2, 2007.

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