During the 1980s, the U.S. launched a national and international agenda that would later be called the Transnational War on Organized Crime. Internally, demands for different penal regulations to prosecute organized crime arose due to the difficulty of securing evidence and witnesses in cases against high-profile organized crime members. This led to the enactment of new laws across various states, increasing prosecutorial power to classify organized crime offenses while lowering the standard of proof required to establish gang membership during a criminal case. Internationally, the U.S. promoted criminal justice reforms across Latin America to align the region’s penal systems with its new organized crime model. In this dissertation, I explore the consequences of this transnational agenda in two domestic contexts. First, in the U.S. case, I examine the effects of the massive expansion of six types of organized crime laws across the country on crime, arrest, and incarceration rates. Second, I study the Colombian case to assess the impact of one of the major criminal justice reforms promoted and sponsored by the U.S. as part of its transnational war against organized crime: the Adversarial Criminal Justice Reform. I selected the Colombian case for three main reasons. First, along with Mexico, Colombia has been a key country in organized crime in the Americas. Second, Colombia and Chile have been leading countries in criminal justice reform, as well as in military and police training in the region. As a result, Colombian prosecutors, judges, police officers, and military agents have trained and guided other Latin American countries in implementing U.S.-promoted policies and strategies. Finally, Colombia is the only country in Latin America that successfully implemented the adversarial criminal justice reform as originally planned, allowing me to isolate the effects of the reform from implementation problems. The results of these three essays suggest that, in the U.S. case, anti-gang reforms may not have significantly impacted crime and incarceration rates. However, in the Colombian case, the adversarial reform had unintended consequences on crime rates, with mixed results regarding the reform’s gains in due process protections