The Supreme Court this morning decided in Kennedy v. Louisiana that the death penalty is unconstitutional for the crime of the rape of a child. The primary reason for the holding is the national consensus the Court found in state laws. When death penalty laws were reenacted after the prior laws were struck down in 1972, only a handful of states included any kind of rape among the new capital offenses. The Court noted that a few states have recently enacted child rape laws, but found the trend insufficient to overcome the consensus.
The decision was also based on a variety of other factors. The Court noted the difficulty of narrowing the cases eligible for the death penalty in the way that homicides have been narrowed. It noted the problem of unreliable child testimony, the impact of lengthy proceedings on the child, and the possibility that the penalty might deter victims from reporting rapes where the perpetrator is a family member. In terms of deterrence, having the same penalty for both rape and murder could have a perverse effect. That equivalence "may remove a strong incentive for the rapist not to kill the victim." The latter reason is why CJLF does not support the death penalty in these cases as a matter of policy, regardless of whether it is constitutional.
The opinion reaffirmed the Court's precedents upholding the death penalty for murder, however. The opinion, written by Justice Anthony Kennedy and joined by the four justices generally considered the "liberal" wing of the Court, declares that its jurisprudence allowing but limiting the death penalty for murder "remains sound." In addition, the Court's ban on the death penalty for nonfatal crimes is expressly limited to crimes against individuals. The decision does not affect federal laws providing the death penalty for crimes against national security, such as treason and espionage.
The dissenting opinion by Justice Alito points out that the Court's method of determining the scope of the Eighth Amendment by looking at legislative consensus fails to fully appreciate the effect that the Court itself has on legislation. A legislature may refrain from passing a law it would otherwise enact because it believes the law would be or might be struck down. The majority opinion notes this objection but fails to genuinely address it.
Eric Posner has this post at Convictions (Slate) on the ratchet problem.