Coutesty of Concurring Opinions:
[Jewish scholars asserted that a Court of Law] that kills [i.e., convicts on a capital crime] once a week is called "destructive." [But a scholar then glossed:] "Once in seventy years." [Two other even more luminary scholars objected], "If we had been on the [Court], there would never have been a person killed." [But] R. Shimeon ben Gamaliel [replied], "They would have increased the number of spillers of blood in Israel."
Apparently, someone did believe that the death penalty was a deterrent. Take that DovBear!