Last verified: April 2026

What the Experiment Is

The Experiment Gesloten Coffeeshopketen (Closed Coffeeshop Chain Experiment) is a government-controlled pilot program to create, for the first time, a fully legal cannabis supply chain in the Netherlands. Licensed growers produce cannabis that is tracked, tested, and delivered to coffeeshops through regulated distribution — closing the “back door” that has been illegal for 50 years.

The experiment was recommended by the Knottnerus Committee (Adviescommissie Experiment Gesloten Coffeeshopketen) in 2018, which concluded that the back door problem could only be assessed through a real-world trial. The Dutch parliament approved the Wet Experiment Gesloten Coffeeshopketen (Closed Coffeeshop Chain Experiment Act) in 2019, establishing the legal framework for the pilot.

The core question: can a legal, regulated supply chain deliver quality cannabis to coffeeshops, reduce criminal involvement, and maintain public health and safety? If the answer is yes, the Netherlands moves toward full legalization. If not, the tolerance system continues — paradox and all.

The experiment aims to determine whether and how quality-controlled cannabis can be supplied to coffee shops in a closed chain, and what the effects are of this on the coffee shop, on crime, on public health, and on nuisance.

Dutch Ministry of Health, Welfare and Sport — Experiment Act Explanatory Memorandum

The 11 Cities and 10 Growers

The experiment involves 11 municipalities selected to represent a geographic, demographic, and policy cross-section of the Netherlands:

Ten licensed growers were selected through a rigorous application process to supply these coffeeshops. The most notable development in the grower landscape was the €57.5 million acquisition of CanAdelaar, a Dutch experiment grower, by Cronos Group, a Canadian publicly traded cannabis company. This was a landmark moment — the first major international cannabis investment in Dutch legal cultivation.

Amsterdam’s involvement is limited to the Oost (East) district. The vast majority of Amsterdam’s ~167 coffeeshops — including all the famous Centrum locations — continue to operate under the traditional tolerance system with their existing (illegal) supply chains. This means tourists visiting the most popular coffeeshops will not notice any change during the experiment period.

Timeline and Phases

The experiment has progressed through several phases, with the full experimental period now underway:

• 2018: Knottnerus Committee recommends the experiment
• 2019: Parliament passes the Experiment Act
• 2020–2022: Grower selection, licensing, and facility construction
• December 2023 — Preparation phase: Licensed growers begin cultivating and building inventory. Coffeeshops in the 11 cities start receiving legal supply alongside their existing stock.
• June 2024 — Transition phase: Coffeeshops in experiment cities gradually shift from illegal to legal supply. Both sources coexist during this period.
• April 7, 2025 — Experimental phase begins: Coffeeshops in the 11 cities must now sell exclusively from licensed growers. The back door is officially closed for these shops. This phase runs for approximately 4 years through ~2029.

The experiment is monitored by Breuer & Intraval (a Dutch research bureau), in collaboration with RAND Europe and the Trimbos Institute (the Netherlands’ leading addiction and mental health research center). Their evaluation will assess impacts on criminal activity, public health, product quality, coffeeshop economics, and street-level drug dealing.

Challenges and the “Fire Letter”

The experiment has not gone smoothly. Several significant challenges have emerged:

• Supply shortages: Licensed growers initially struggled to produce enough variety and volume to replace the established illegal supply chain. Coffeeshop owners in experiment cities reported that customers were dissatisfied with limited strain selection and inconsistent availability.
• The “fire letter” (brandbrief): Coffeeshop owners in experiment cities sent a formal complaint letter to the government warning that the transition was threatening their businesses. Customers were leaving for non-experiment cities or returning to street dealers, exactly the opposite of the experiment’s goals.
• Price pressure: Legal cannabis must compete on price with illegal supply that carries no tax, regulation, or compliance costs. Licensed growers face significant overhead — security requirements, testing mandates, track-and-trace systems — that criminal operations do not.
• Quality expectations: Dutch coffeeshop customers are among the most discerning in the world. After decades of access to Amsterdam-bred genetics, customers in experiment cities expected comparable or superior quality from legal growers. Meeting that bar proved difficult in the early phases.

Despite these challenges, the experiment continues and the April 2025 transition to exclusive legal supply represents the most significant step. The next 4 years of data will determine whether the model is viable at scale.

The D66 Coalition and What Comes Next

The experiment’s political context has shifted dramatically. Following the February 2026 coalition formation, the Netherlands is governed by the most cannabis-reform-friendly government in its history. D66, the social-liberal party that has long championed cannabis regulation, leads the coalition, with Rob Jetten serving as formateur.

D66 has historically advocated for:

• Full legalization and regulation of the cannabis supply chain
• Treating cannabis policy as a public health issue rather than a criminal justice issue
• Expanding the experiment to more cities if results are positive
• Ending the front door / back door paradox permanently

This is a dramatic change from previous coalitions. The VVD/CDA/ChristenUnie governments that preceded this coalition ranged from skeptical to actively hostile toward coffeeshop culture. The wietpas debacle of 2012 was driven by these parties.

If the experiment produces positive results under a sympathetic government, the path to full legalization becomes politically viable for the first time. The Netherlands could transition from tolerance to actual legal regulation — potentially resolving the 50-year-old paradox that has defined Dutch drug policy since 1976.

For tourists, the experiment is mostly invisible. The coffeeshops you visit in Centrum, Jordaan, and De Pijp are not part of the experiment and continue operating exactly as before. But the outcome of this experiment may determine whether the coffeeshop system survives, evolves, or is eventually replaced by something entirely new.