That is the standard for the Eighth Amendment's protection--the Constitution protects inmates in prisons and jails from "deliberate indifference to a serious medical need."  There are few medical needs more serious than drug addiction, but unfortunately very few prisons and jails do enough to provide tools to inmates to help treat and overcome addiction.  In a well-researched article in today' New York Times, Katie Zezima and Abby Goodnough discuss one of the barriers to such treatment--the contraband uses of medicines used to deal with addiction.  But, if jails don't make this medicine available for inmates going through painful withdrawal or inmates trying to overcome addiction, it is hardly surprising that the inmates will go to extraordinary lengths to get that treatment illicitly.

Worth reading.