4. The Dutch closed cannabis supply chain experiment: background, design of the evaluation study and challenges

Introduction and aims: In the Netherlands, it is illegal to produce cannabis or supply it to coffeeshops, but the sale for personal use is tolerated under strict conditions. In 2017, the coalition agreement of the former cabinet included a proposal to conduct an experiment with the legal supply of cannabis to coffeeshops in a closed supply chain. Legislation to allow the experiment entered into force on 1 July 2020. The aim of this experiment, a milestone in Dutch drug policy, is to ascertain whether or not it is possible to regulate a quality-controlled supply of cannabis to coffeeshops and to study the effects of a regulated supply chain on crime, safety, public nuisance and public health.

Design and methods: A consortium of three institutes (Trimbos Institute, RAND Europe and Breuer&Intraval) will conduct the evaluation of this experiment, which is designed as a quasiexperimental study with an experimental and control group of municipalities. Pre-post assessments will be conducted over a period of 5 years. A combination of qualitative and quantitative methods will be applied, including surveys among coffeeshop visitors, interviews with stakeholders, surveys with neighbourhood residents, analysis of registration data, ethnographic field work, and chemical analysis of cannabis samples.

Key findings: Baseline data collection is ongoing; results are not yet available (January 2022).

Discussions: An overview will be given of the background, objectives and outlines of the experiment and the design and state of play of the evaluation study. Experiences in the Netherlands may inform scientists and policy makers in other countries where cannabis policies are evolving.