Study: Germany Marijuana Legalization Hasn’t Increased Driving While High

(Photo credit: SusanneSchulz/iStock via Getty Images).

A new analysis published by The Lancet Regional Health – Europe found no significant short-term change in adult marijuana use or driving under the influence of marijuana in Germany in the months after the country legalized adult possession and home cultivation. Researchers from University Medical Centre Hamburg-Eppendorf, the Federal Highway and Transport Research Institute in Bergisch Gladbach, Germany, and the University of Leipzig analyzed two nationwide, cross-sectional population surveys in Germany and Austria, using Austria as a control where marijuana remained illegal. The surveys were conducted before legalization (Nov–Dec 2023) and after legalization (Nov 2024–Jan 2025).

In Germany, past-year marijuana use rose from 12.1% to 14.4%, but the increase was not statistically different from Austria’s change over the same period, according to the study’s difference-in-differences analysis. Among at least monthly marijuana users, self-reported driving under the influence of marijuana actually fell slightly from 28.5% to 26.8%.

The study also examined “DUIC(+)” episodes—driving after marijuana use combined with alcohol or other drugs—and found they accounted for 21.5% of reported episodes at the follow-up point. DUIC involving only marijuana was most common among daily users, while DUIC with alcohol or other drugs was most common among weekly users. Researchers said longer-term monitoring is needed to evaluate traffic safety as Germany’s reforms continue to roll out, including the updated THC driving limits the country adopted in August 2024.