This essay first discusses the history of solitary confinement as a prison technique and its negative psychological consequences. It then recounts the international standards for prison conditions and, comparatively, the protection afforded under the Eighth Amendment of the US Constitution. Next it will then discuss progressive European prison standards and protection of international human rights. It concludes that  US solitary confinement practices contravene international treaty law, violate established international norms, and do not represent sound foreign policy.

http://www.auilr.org/pdf/21/21-1-5.pdf