Germany’s partial legalisation of cannabis in April 2024 did not result in a statistically significant increase in driving under the influence of cannabis (DUIC) during the policy’s first year, according to a new study published in The Lancet Regional Health.
The research, which used Austria as a control group in a difference-in-differences analysis, tracked self-reported DUIC among monthly cannabis users in both countries. In Germany, the rate of drug driving decreased slightly from 28.5% before legalisation to 26.8% after.
When compared to trends in Austria, where cannabis remains illegal, researchers determined that the difference was not statistically significant.
The cultivation and possession of cannabis for adults was partially legalised in April 2024, following the introduction of the CanG Act. A new legal limit of 3.5 nanograms of THC per millilitre of blood serum for driving purposes was established in August 2024.
“Researchers at the University Medical Center Hamburg-Eppendorf (UKE) investigated the short-term effects of the partial legalization of cannabis for adults in Germany and found no significant changes compared to the period before the law was amended,” a press release covering the study said.
The study also examined overall cannabis use patterns. Past-year cannabis use in Germany rose from 12.1% to 14.4%, though again this increase did not differ significantly from Austria, where cannabis remains prohibited.
This study is the first nationwide evaluation of cannabis legalisation in a European country,” the authors wrote. “The results show neither a significant short-term shift in cannabis use prevalence nor in the prevalence of DUIC among cannabis users following legalisation in Germany.”
“While further monitoring of possible negative consequences of cannabis legalisation is required, the German cannabis legalisation model appears to broadly align with public health goals with respect to prevalence of use and traffic safety,” they added.
The study, which was funded by the Federal Highway and Transport Research Institute, is the latest to show that predicted negative consequences following cannabis reform fail to materialise.
A 2025 study found that cannabis use amongst German teenagers aged 12-17 fell from 6.7% to 6.1% after legalisation.
Germany’s former health minister Karl Lauterbach, who spearheaded legalisation efforts in the country, said at the time of publishing that the results confirmed “what the goal of legalisation was: through the debate about dangers for children and adolescents, their consumption does not increase or even decreases.”