Arguing Unconvincingly for the Illegality of Marijuana

The idea that marijuana legalization would impose more costs on society than it would relieve should not be dismissed out of hand, but I've never read any such argument that came within miles of convincing me. Take the Sunday op-ed from the LA Times, written by a retired ONDCP official:

Finally, legalizing marijuana would in no way ensure that the most vicious drug-related problems -- violence, economic-related crime, street gang activity -- would disappear. Most of those problems stem from the cocaine, heroin and methamphetamine markets. Marijuana's share of the black market is modest (the cocaine market is three times larger), and the money that is spent on the drug is spread over so many users and distributors that few are working with amounts that motivate or encourage high levels of crime.

On a global level, the marijuana market may not be that big, but on a global level, GM is a relatively insignificant car company. However, both matter enormously to the US. According to John Walters, marijuana sales account for 62 percent of the income of Mexican traffickers, which are the groups that present the greatest concern for American policy makers. No one is arguing that legalizing pot would make gangs in the US or Mexico disappear, but if we could deprive them of two thirds of their income, this would shrink their power enormously. Now, perhaps the author has devised a method of disaggregating Mexican drug crimes so as to determine which stem from marijuana trafficking and which are due to cocaine and meth, but if he has, he offers no hint of it. Otherwise, given the affirmation by Mexican and American policy makers about the percentage of Mexican gangs profits owing to weed, and given the stratospheric levels of crime in the regions where marijuana is produced in Mexico, there isn't much basis for blanket statements like, "[m]ost of those problems stem from the cocaine, heroin and methamphetamine markets".

A second flaw:

Only about half a percent of the total prison population was there for marijuana possession [unrelated to dealing], he found.

The point is that it's such a small number as to be almost negligible. However, in absolute terms, that's more than 10,000 people doing time for using, not selling, pot. That's a scandal.