By Vivian Mateos Zúñiga and David A. Shirk

Scholars and legalization advocates have argued that the legalization of cannabis would help curb drug flows from Mexico and weaken criminal organizations south of the border. However, there is little empirical research examining how the legalization of cannabis for medical and recreational purposes at the state-level in the United States has affected production levels and flows of cannabis from Mexico. To examine the theory that drug legalization reduces the incentives and profits for international drug trafficking organizations (DTOs), the authors draw on a mixed methodological approach that includes descriptive and inferential statistical analysis of data from the U.S. State Department, archival research using primary and open-source documents from U.S. and Mexican government and media sources, and interviews with U.S. officials and security experts to analyze trends in seizures and legalization. Drawing on this information, we employ a series of statistical tests to examine the relationship of greater legal access to cannabis in U.S. states—measured by the percentage of the population living in states with access to legalized medical or recreational marijuana over time—to illegal eradication and seizures of drugs by Mexican government and U.S. border authorities. We use this measurable outcome as a proxy for illicit drug production and transshipment in Mexico. We find a substantial and statistically significant decrease in the amounts of cannabis apprehended by Mexican and U.S. border authorities in relation to the rate of legalization in the United States using our measurements of drug legalization. At the same time, the authors find additional statistically significant evidence that, as legal access to cannabis has increased, flows of other illicit drugs increased simultaneously, suggesting that criminal organizations have diversified into other drugs to remain profitable, particularly heroin and methamphetamine. Our findings do not find any evidence that cocaine has been significantly affected, for reasons we discuss.   

Volume 19, Number 1 January 2022 San Diego: Justice in Mexico, University of San Diego, 2022.