BACKGROUND:In 2009, Mexican Federal Government enacted "narcomenudeo" reforms decriminalizing possession of small amounts of drugs, delegating prosecution of retail drug sales to the state courts, and mandating treatment diversion for habitual drug users. There has been insufficient effort to formally assess the decriminalization policy's population-level impact, despite mounting interest in analagous reforms across the globe. METHODS:Using a dataset of municipal police incident reports, we examined patterns of drug possession, and violent and non-violent crime arrests between January 2009 and December 2014. A hierarchical panel data analysis with random effects was conducted to assess the impact of narcomenudeo's drug decriminalization provision. RESULTS:The reforms had no significant impact on the number of drug possession or violent crime arrests, after controlling for other variables (e.g. time trends, electoral cycles, and precinct-level socioeconomic factors). Time periods directly preceding local elections were observed to be statistically associated with elevated arrest volume. CONCLUSIONS:Analysis of police statistics parallel prior findings that Mexico's reform decriminalizing small amounts of drugs does not appear to have significantly shifted drug law enforcement in Tijuana. More research is required to fully understand the policy transformation process for drug decriminalization and other structural interventions in Mexico and similar regional and international efforts. Observed relationship between policing and political cycles echo associations in other settings whereby law-and-order activities increase during mayoral electoral campaigns.