Summarize the article "Rethinking Proportionality Under The Cruel and Unusual Punishments Clause" at http://scholarship.law.ufl.edu/cgi/viewcontent.cgi?article=1274&context=facultypub

The article proposes that proportionality reviews are crucial in efforts to correctly interpret the Cruel and Unusual Punishments Clause. Additionally, proportionality highlights a retributive rather than a restorative concept of justice. Thus, to quantify excessiveness, one would need to consult prevailing moral standards rather than popular, shifting definitions of cruelty.
This article proposes that new approaches to proportionality would allow the Supreme Court to nullify death penalty verdicts for non-homicidal cases and to restrict life-without-parole sentences for juvenile offenders. The article states that a proportionality review is critical because the Supreme Court has failed to furnish a rational definition of proportionality and to employ concrete solutions that ensure proportionality.
In the past, the Supreme Court often rejected death penalties or life sentences even when there was no clear societal consensus against them. In these instances, the Court relied on a fictionalized consensus to justify its own arbitrary verdicts. At other times, the Court relied on its own independent judgment to define cruel and unusual punishment. In short, the Court lacked a definitive standard for measuring excessiveness.
As history shows, the original Framers interpreted the Eighth amendment in light of prior practice. Later, nineteenth-century law experts supported the notion that the Punishment Clauses rejected both excessive and barbaric retribution. However, they based this support on entrenched definitions of excessiveness. Basically, the Court needs a clear standard for defining "cruel and unusual punishment," a standard that must not be influenced by shifting public opinion, the Court's independent judgment, or the machinations of legislators.