States with the death penalty have lower murder rates.

This is not necessarily true.

http://www.cracked.com/article_19489_5-terrible-ideas-that-solved-huge-global-problems.html

To summarize what this article says, you don't need violence to deter people from committing crimes.  All these different countries used more passive, mood altering means to change people's mindsets.  What strikes me the most is the "prison" in Norway, where the criminals have as much freedom as a normal citizen.  Of course, if you decided to skip the article, you'd probably be saying "What?"  But it's true.  Statistics have shown that the criminals in this place are 1/3 less likely to go back to a life of crime than their American counterpoints.  1/3 is a huge difference.  Think about what would happen if the death penalty is incorporated.  Chances are, the crime rates will increase.  But why does this happen?  I speculate that because of the cruelty in the usual prisons would harden these criminals and make them angry towards society.  With the comfortable lifestyle, I would be more confident to release these happy criminals.  Mind blowing, isn't it?