They count between three and 18 lives that would be saved by the execution of each convicted killer. ...Personally, I think I'd be in favor of the death penalty even if it were only a question of one life being saved by it; I see no reason to spare convicted murderers' lives and have absolutely no sympathy for them. That DNA and other evidence is overturning convictions is wonderful, but I think that because we now have that technology we'll have fewer and fewer mistakes in the first place, so this will no longer be an issue. I may be biased in that I don't see how it's possible that it wouldn't deter crime; not only is it less likely to have idiotic releases of criminals (the infamous Illinois release is estimated to have cost 150 lives in the just six years since it happened), but [for example] criminals who already would be getting 25 to life if caught would have no disincentive to stop them from killing a person if they felt that person was a threat.
"Science does really draw a conclusion. It did. There is no question about it," said Naci Mocan, an economics professor at the University of Colorado at Denver. "The conclusion is there is a deterrent effect."
A 2003 study he co-authored, and a 2006 study that re-examined the data, found that each execution results in five fewer homicides, and commuting a death sentence means five more homicides. "The results are robust, they don't really go away," he said. "I oppose the death penalty. But my results show that the death penalty (deters) — what am I going to do, hide them?
Regardless of my personal beliefs, though, it seems that there is a clear benefit to having the death penalty. People seem to forget that this does not mean it is required to be meted out; but I think that particularly for the obvious and more gruesome cases, the option must always be available. More importantly, this is a policy that will only negatively impact a tiny population - convicted murderers who have lost all their appeals - while saving the lives of innocent people. I don't understand how people aren't jumping at such an opportunity.