While I think it is best to just abolish the death penalty, why is it so hard to painlessly kill someone with guaranteed results? Can't they just be knocked out with a large dose of general anesthetic and then be injected with a lethal overdose of heroin (the rare few who do happen to wake up or who are not affected by the general anesthetic would be feeling pretty good before dying). It doesn't seem like rocket science to me.
Cattle in the stockyard get it pretty good in some cases. And that actually serves some purpose that is not punitive. The real problem with the death
penalty is its utter unfairness and being skewed toward the poor, the black, the unpopular, and about any other un you can think of.