The difference is looking at federal prisons vs arrests and other prisons. Federal is for more egregious crimes, so it would make sense that less of them are for pot and more for harsher drugs.

It is difficult, but we have to try to be aware of the biases in the data we have. I should have mentioned in my first post that those were just federal stats. But I try to break down more in another comment state and jails, specifically about possession statistics.

I don't know, I was just pointing out the fact that people in federal prison are not there for smoking weed on the porch. I don't have the numbers handy, but I would guess that a vast majority of the marijuana arrests in your article result in a fine or probation at the very most.

Which I happen to agree is a waste of resources and probably does more harm than good by getting people started "in the system".