I was on a panel recently where I enumerated some reasons why I think it is a mistake to mass incarcerate drug-addicted criminal offenders. The chair of the panel cracked “You forgot to mention that they use even more drugs behind bars than they do on the street!”. The other guests and members of the audience nodded knowingly.

Insert Al Gore-esque sigh here.

I have written before about how many people who have never been in a prison are confident that they know what prisons are like. This is one example: the “common knowledge” that drugs are just as available inside the stony lonesome as they are outside. I deflate this myth with research evidence in my piece today at Washington Post’s Wonkblog.