From one of the comments further down in the article.
http://www.denvergov.org/Portals/720/documents/statistics/2014/XCitywide_Reported_Offenses_2014.pdf
Things are not always what they seem. Generally speaking, I'm against the feds taking a position on private behavior by individuals. Prohibiting anything from an individual should be the last resort. What troubles me is that the feds have gone so far in controlling behaviors. We spend so much, with little or no benefit. It seems to be a very poor return on investment for our limited tax revenue.
The other side of the coin is the social cost to lives, and contribution. Not saying that all pot users are addle-brained, or that they produce nothing, but I think I can safely say that there's little social benefit to pot consumption. Of course, the same can be said of alcohol, and there is a distinct social cost(lost productivity, intox manslaughter, etc) involved. Pot may not be as bad in most respects, but there is a cost involved.
Complex social calculus.