It costs a lot more to kill someone than it does to keep him alive in prison for the rest of his life. The cost of all the appeals that result from a death sentence is higher than the average cost of keeping the prisoner alive until the end of his natural life. The last figure I saw was $3,000,000 in legal and court costs for each prisoner executed. If the average criminal is going to live 40 years at $40,000 per year, it is considerably cheaper to keep him alive.

There is a lot of talk about "streamlining the appeals process" in order to reduce costs and speed up executions. This can only increase the likelihood of executing innocent people.