Drugs and Guns
I wrote this comment as part of a thread over at Registan, liked it, so wrote it over here. I had originally planned to write something completely different, that Christianity, with its belief in angels, a man-god, and eternal life and damnation, wasn't so advanced that Tom Friedman should be crowing
There is an important relationship that emerges in all contraband markets. Once one steps over the line, the cost of expanding one's inventory with additional types of contraband, legally speaking, is low. It will be prison in either case.
It's not a coincidence that one group, call them mafia, often controls drugs, gambling, guns and prostitution in a particular area. Certain aspects of the contraband industry, once learned, are useful in the trade in any of its particulars. Examples include learning how to launder money, secure contraband storage, and learning what public officials are corrupt.
Therefore, legalization of heroin eradicates a community of criminals who might consider dealing in weapons, removes some profit from those who already deal in both, and reduces, by millions, the number of people who deal/traffic with these criminals, and who, therefore, might tend to by sympathetic with their interests (i.e. few of America's heroin users consider Afghani eradication efforts, but I'm sure some have, and can't think it is all for the best).
If one adds the fact that most criminal enterprises require firearms purchases, I don't believe it is excessive to say there exists a great deal of corporate "synergy" between the drug and arms trades.