Would legal California marijuana really hurt the cartels?

White House drug czar Gil Kerlikowke is hailing the release of a new Rand report which finds that if Californians vote to legalize marijuana on Nov. 2, it won’t put much of a dent in the profits of Mexican drug cartels:

"This report shows that despite the millions spent on marketing the idea, legalized marijuana won’t reduce the revenue or violence generated by Mexican drug-trafficking organizations," Kerlikowske said.

The report finds that legalized pot in California would cut drug export profits by about 2 to 4 percent. There’s a big however though: 

However, the impact of legalization on Mexican drug trafficking organizations’ bottom line could be magnified if marijuana cultivated in California is smuggled into other states, according to the study. After legalization, if low-cost, high-quality marijuana produced in California dominates the U.S. marijuana market, then the Mexican drug trafficking organizations’ revenue from exporting marijuana could decline by more than 65 percent and probably closer to 85 percent. In this scenario, results from the RAND study suggest the drug trafficking organizations would lose roughly 20 percent of their total drug export revenues.

With this caveat, couldn’t the report be viewed less as a case against legalization in California than an argument for extending it nationwide?

To be fair to Kerlikoswske, I’m not sure that framing this issue in terms of it’s effect on Mexican drug cartels is the most effective argument. Things shouldn’t be legalized just because criminals are making money off them. The more important question is whether the social ill from marijuana justifies the cost of keeping it illegal.