What is the Wietexperiment in the Netherlands?

The Wietexperiment is a time-limited Dutch trial with a “gesloten coffeeshopketen”, a closed coffeeshop supply chain. According to the Rijksoverheid, it runs on a small scale in ten municipalities. Coffeeshops there sell regulated, quality-controlled cannabis that comes from at most ten selected growing businesses. This article explains the aim, the process and the supervision, based on information from the Dutch government (status of this check: 26 October 2026).

Why the Netherlands is running the experiment

The background is the coffeeshop system. Sales are tolerated, but production and delivery of cannabis are illegal. The Rijksoverheid notes that the toleration policy brings problems, for example for public order, public health and infiltrated structures. The experiment is meant to examine how a regulated supply chain works in practice. The article How does the coffeeshop system work in the Netherlands? explains how the coffeeshop system works.

How the experiment is set up

In the ten participating municipalities, coffeeshops sell regulated cannabis. It is grown by at most ten selected growing businesses that were chosen in a selection procedure. All conditions for participating coffeeshops are set out in the Dutch “Besluit experiment gesloten coffeeshopketen” (Decree on the closed coffeeshop chain experiment). Supervision lies with the municipalities and the Inspectie Justitie en Veiligheid (Inspectorate for Justice and Security). They check that no cannabis from the illegal circuit enters the experiment and that nothing from the experiment is processed or sold outside it. The Dutch food safety authority NVWA monitors, among other things, the quality of the cannabis grown and the packaging requirements.

The five phases

The experiment consists of five phases that govern the transition from the current situation to the experiment and back again.

• Preparation phase from 1 July 2020: the growing businesses were selected and appointed, and the municipalities adjusted their rules.
• Start-up phase from 15 December 2023: coffeeshops in Tilburg and Breda were allowed to sell regulated products alongside tolerated ones and tested all processes on a small scale.
• Transition phase from 17 June 2024 to 7 April 2025: coffeeshops were allowed to hold and sell both tolerated and regulated products.
• Experimental phase since 7 April 2025: the coffeeshops in the participating municipalities sell only regulated products.
• Wind-down phase after the experiment: the normal rules then apply again, unless the government decides otherwise.

Duration and research

According to the Rijksoverheid, the experimental phase basically lasts four years and can be extended by one and a half years. The four-year duration is set by law. Ending the experiment as a whole would require a separate law. In special cases, for example to protect public health or public order, the responsible ministers can stop the experiment in an individual municipality. Researchers observe the effects and record their findings in an annual report. Before the end of the experimental phase, an independent monitoring and evaluation committee assesses the experiment.

What results can mean

A pilot shows what happens under certain conditions. It does not automatically show what would happen across the whole country. Ten municipalities, the duration and local particularities limit how much the results can tell us. Specialist media also report on first results. Their assessment can be shortened, so figures should always be checked against the reports of the research team. An article of its own covers the interim status: What does the first interim report on the Wietexperiment show?

What a pilot project has to measure

For a trial to tell us anything, it has to set out in advance what it measures. This includes baseline values before the start, comparison groups and fixed points in time for evaluation. Anyone reading a first report should therefore ask about the comparison and not only about the number. It is especially worth looking at the original report when a message comes from the cannabis industry.

Typical misreadings of first results

• A figure without a sample size is hard to interpret.
• A survey is not automatically meaningful for the whole population.
• A difference between two small groups can be due to chance.
• A short period shows snapshots, not trends.

These points apply to every evaluation and say nothing against the experiment itself.

What matters for Germany

German law takes a different route from the Netherlands: home cultivation (§ 9 KCanG) and licensed cannabis associations (§ 11 KCanG), whose members grow together. Selling in shops is not provided for. The question of whether the law has reduced the black market in Germany is covered in the article Did the law reduce the black market?

Prevention remains central

A regulated market does not replace prevention. The young brain is in an important stage of development, and consumption can affect that development. With regular use, psychological dependence can develop (drugcom.de). This applies regardless of where the product comes from. The article What role does the THC content play in the risk? explains further connections.

Next steps

Read the Rijksoverheid page on the experiment and pay attention to the date, the municipalities and the method. The page shows no visible update date. An overview of other countries is given in the article Which countries have legalised cannabis?