Proposition 19, which would partially legalize marijuana in California, would do little to curtail the violent Mexican organizations that smuggle it across the border, according to a new study by drug policy researchers that takes aim at one of the main arguments proponents have made for the initiative. The report released by Rand Corp. estimates that legalized marijuana could displace the Mexican marijuana sold in California, but concludes that would erase no more than 2% to 4% of the revenues the gangs receive from drug exports.