Gonçalves, R., Lourenço, A., & Marreiros, H. (2025). Measuring drug policy evolution: A cross-country analysis. International Journal of Drug Policy, 138. https://doi.org/10.1016/j.drugpo.2025.104750

This paper develops a quantitative framework to systematically measure and compare the evolution of drug policies across countries and over time. Recognizing that existing research often lacks standardized tools, the study introduces the Illicit Drugs Policy Indexes (IDPI), built using leximetrics to translate legal texts into comparable numerical indicators. The methodology involved constructing legislative timelines, coding procedures, and validating data through expert input. Indicators were designed to classify policies as either health-oriented, emphasizing assistance to drug users, or criminal-oriented, emphasizing punishment. The IDPI covers laws on consumption, possession, and trafficking—further subdivided into cultivation, production, and distribution—while distinguishing between cannabis and other drugs. Analyzing seven countries (Australia, Canada, France, Italy, Netherlands, Portugal, and the UK) from 1996 to 2016, the study identified key turning points, such as Portugal’s 2001 decriminalization and Italy’s fluctuating cannabis policies. Results highlight significant cross-country variation, with some moving toward leniency and others retaining stricter approaches. The IDPI offers a standardized tool for comparative analysis, though it measures only “law in books” rather than real-world enforcement.