The death penalty is an archaic and unconstitutional form of revenge in the criminal justice system.
It directly violates the Constitution by being cruel and unusual.
The death penalty is an unnecessary burden on tax payers. The costs of required appeals and the execution are often far higher than the cost of sustaining a prisoner for the rest of his or her life.
And the death penalty is barbaric, reminiscent of Hammurabi's original code of laws: "An eye for an eye..." Thousands of years later, humanity has certainly progressed. Now it's time for the United States to move forward.
Life without parole is just fine. And much cheaper.