For over a century the international community has widely accepted a policy of universal drug prohibition. However, an increasing number of countries have been willing to experiment with progressive drug policies as the shortcomings of strict prohibition become more clear. This thesis is a study of the structures of drug laws in four countries β the Netherlands, Portugal, the United States, and Mexico β and their economic, public health, and human rights outcomes. The policies range in restrictiveness from the decriminalization of all drugs in Portugal to complete criminalization in Mexico. This thesis focuses on cannabis and heroin, two drugs which differ markedly in their risk for addiction and acute harm. A wide range of sources in the drug policy literature was analyzed. Evidence suggests that progressive policies in Portugal and the Netherlands have not significantly increased drug use and have led to numerous favorable public health outcomes. States in America that have legalized marijuana face many legal and economic challenges, and they should be observed closely as their policies develop further. Strict supply-control enforcement in Mexico has, on the other hand, led to an extreme upsurge in violent crime. These results suggest that in the future policymakers should drastically reallocate resources from ineffective supply-side strategies and pursue proven policies centered on public health and the protection of human rights