Do We Still Need the Death Penalty?

Capital punishment is on the decline in the US, though it's still on the books in 32 states with more than 3000 inmates on death row. It's also back in the news since federal prosecutors said they would seek death for the Boston Marathon bomber. In addition, death-penalty states can't get the drugs used for lethal injections, because European companies won't import them for that purpose any more, and replacements used in two recent executions have raised questions about "cruel and unusual punishment." Legislators in some states want to go back to gas chambers, firing squads and hangings. Is the "ultimate penalty" a deterrent? Can it ever be "humane?"