As California voters, along with voters in four other states, prepare in 10 days to decide on ballot measures that would expand the legalization of marijuana in the U.S., opinions differ on how much the measure would hurt the illegal drug trade.

Violence connected to Mexican drug cartels routinely spills over the border into areas of the U.S. southwest. But a study by the RAND Drug Policy Research Center claims that any effect of a legalization measure on the cartels would be minimal at best.

The illegal marijuana trade reportedly generates a combined $18 billion to 39 billion in revenue annually, and comprises 60 percent of the revenue made by Mexican drug traffickers. But the study’s researchers disagreed, saying Mexican cartels’ gross revenues from selling marijuana wholesale in the United States is much less, closer to $1.5 to 2 billion.

“The claim that 60 percent of Mexican DTO gross drug export revenues comes from marijuana is not credible,” the report states. “There is no public documentation about how this figure is derived, and government analyses reveal great uncertainty. RAND’s exploratory analysis on this point suggests that 15–26 percent is a more credible range.”

Meanwhile an International Centre for Science in Drug Policy report commissioned by the U.S. government concluded Oct. 7 that cannabis prohibition has failed.

Among its findings, it discovered that the U.S. government increased its anti-drug funding from $1.5 billion in 1981 to $18 billion in 2002, but the potency of cannabis increased by 145 percent while the price decreased by 58 percent. Dr. Evan Wood, founder of the organization, said that the nation should start exploring other options.

“Data, collected and paid for by the U.S. government, clearly shows that prohibition has not reduced cannabis consumption or supply. Since prohibition is not working, we need new approaches to better address the harms of cannabis use,” Wood wrote in the report. “Scientific evidence clearly shows that regulatory tools have the potential to effectively reduce rates of cannabis-related harm.”

Wood said widespread legalization of pot could effectively end the drug trade on American soil by eliminating many gangs and other organized crime groups.

“Legalization and strict regulation are more likely to be effective at eliminating the role of organized crime in marijuana production and distribution, because the profit motive is effectively removed,” said Wood.