How is it that the death penalty is "cruel and unusual punishment" for a 17 year old but not for an 18 year old?
In my humble opinion because a 17 year old is not legally considered a responsible member of society while an 18 year old is.
Does the question of whether a punishment is "cruel and unusual" depend on who its applied to? Is it cruel for one person but not for another?
Sure. Many of the things that were done in Abu Graib would not bother us in America the least, but would certainly be defined as cruel and unusual to the individuals involved.
In order to make this ruling though, one probably has to define "cruel and unusual," which might or might not include that legal distinction I made above between 18 year olds and 17 year olds.