I think some college campuses try to walk the line with under age drinking. A quick search shows Purdue has a policy that grants students amnesty in the event of alcohol poisonings [1]. I don't know if anyone has run numbers to see the net effects of such a policy.

I imagine that it removes some of the teeth, but if the negative aspects associated with drinking decline, then it seems like a good basis for arguing that similar policies should be applied to harder drugs, even if they remain illegal.

[1] http://www.purdueexponent.org/campus/article_2c255e7c-a2a4-5...