Publications

Second Interim Report on the Evaluation of the Act on the Handling of Cannabis for Non-Medical Use (EKOCAN) (Summary available in English; full text in German. Publication date: 1^st April 2026)

First Interim Report on the Evaluation of the Act on the Handling of Cannabis for Non-Medical Use (EKOCAN) (Summary available in English; full text in German. Publication date: 29^th September 2025)

Here you can find study protocols for various sub-areas of the project.
They document, among other things, the planned data collection and/or analysis steps for different data sources.

Study protocol for the survey of cannabis users and non-users (in German)

Supply and demand of medical cannabis in Germany after legalisation: exploring 12 months of data from an online dispensary

Manthey, J., Giesmann, M., Verthein, U. & Kilian, C. (2026). International Journal of Drug Policy, 155, 105417. https://doi.org/10.1016/j.drugpo.2026.105417

Increase in Cannabis-Specific Hospital Admissions After Partial Legalization in Germany: A Nationwide Time-Series Analysis

Manthey, J., Radas, S. & Kraus, L. (2026). Dtsch Arztebl Int 123(15). https://doi.org/10.3238/arztebl.m2026.0123

Short-term effects of cannabis legalisation in Germany on driving under the influence of cannabis: a difference-in-differences analysis using Austria as a control

Schranz, A., Knoche-Becker, A., Rosenkranz, M., Verthein, U., & Manthey, J. (2026). The Lancet Regional Health - Europe, 63, 101593. https://doi.org/10.1016/j.lanepe.2026.101593

Act on Handling of Cannabis for Non-Medical Use - First Results of Evaluation

Iberl, B., Kinzig, J., Rebmann, F., Ribeiro Marques, C., & Schreier, S. (2025). Deutsche Richterzeitung (DRiZ) 103 (11), S. 414-419.

Legal and Illegal Sources of Cannabis in Germany Shortly After Legalisation

Manthey, J., Klosterhalfen, S., Kotz, D., Rosenkranz, M., Schranz, A., & Verthein, U. (2025). Int J Ment Health Addiction. https://doi.org/10.1007/s11469-025-01574-3

Correlates of driving under the influence of cannabis: a latent class analysis

Schranz, A., Verthein, U., Rosenkranz, M., Knoche-Becker, A., & Manthey, J. (2025). J Safety Res, 95, 330–337. https://doi.org/10.1016/j.jsr.2025.10.012

What proportion of people who use cannabis in Germany have spoken with their general practitioner about their consumption? A repeated cross-sectional representative population survey

Borchardt, B., Klosterhalfen, S. & Kotz, D. (2025). J Cannabis Res 7, 76. https://doi.org/10.1186/s42238-025-00329-0

“Those pot heads” – perceived external stigma and self-stigma among cannabis users in Germany: prevalence and associations with socio-demographics, cannabis use patterns and psychological distress

Rosenkranz, M., Schranz, A., Verthein, U., Schomerus, G., Speerforck, S., & Manthey, J. (2025). J Cannabis Res, 7, 66. https://doi.org/10.1186/s42238-025-00328-1

Germany's cannabis act: a catalyst for European drug policy reform?

Manthey, J., Rehm, J., & Verthein, U. (2024). The Lancet Regional Health - Europe, 42, 100929. https://doi.org/10.1016/j.lanepe.2024.100929

Cannabis Use in Germany: Frequency, Routes of Administration, and Co-use of Inhaled Nicotine or Tobacco Products

Kotz, D., Kastaun, S., Manthey, J., Hoch, E., & Klosterhalfen, S. (2024). Dtsch Arztebl International, 121(2), 52–57. https://doi.org/10.3238/arztebl.m2023.0237