Support for capital punishment is, of course, usually associated with the political right. But the lead author of a new paper making what might be termed the "big government" case for the death penalty is the noted liberal scholar Cass Sunstein. The paper draws in part on a study conducted at Emory University, which found a direct association between the reauthorization of the death penalty, in 1977, and reduced homicide rates. The Emory researchers' "conservative estimate" was that on average, every execution deters eighteen murders. Sunstein and his co-author argue that this calculus makes the death penalty not just morally licit but morally required. A government that fails to make use of it, they write, is effectively condemning large numbers of its citizens to death—a sin of omission like failing to protect the environment or to provide adequate health care. "If each execution is saving many lives," they conclude, "the harms of capital punishment would have to be very great to justify its abolition, far greater than most critics have heretofore alleged."

Abstract:
Recent evidence suggests that capital punishment may have a significant deterrent effect, preventing as many eighteen or more murders for each execution. This evidence greatly unsettles moral objections to the death penalty, because it suggests that a refusal to impose that penalty condemns numerous innocent people to death. Capital punishment thus presents a life-life tradeoff, and a serious commitment to the sanctity of human life may well compel, rather than forbid, that form of punishment. Moral objections to the death penalty frequently depend on a distinction between acts and omissions, but that distinction is misleading in this context, because government is a special kind of moral agent. The familiar problems with capital punishment - potential error, irreversibility, arbitrariness, and racial skew - do not argue in favor of abolition, because the world of homicide suffers from those same problems in even more acute form. The widespread failure to appreciate the life-life tradeoffs involved in capital punishment may depend on cognitive processes that fail to treat "statistical lives" with the seriousness that they deserve.