Our thanks go to all those involved in the writing and production of this book. We owe
a debt of gratitude to all the contributors for their chapters and for their forbearance in
the long time it has taken to be ﬁnally published. Our thanks go to Dan Saunders who
produced the cover image and to Shibu Raman for producing the drawings for Chapter 5.
We thank the Dutch Ministry of Housing, Physical Planning and Environment for
supporting the preparation of this book, in particular Japp van Staalduine.
It has become a habit that following completion of a research programme, a review
or assessment is performed. Partly to justify the money and efforts that went into the
programme and partly to identify novel directions for new programmes. Following
this tradition, the sponsor of the International Cooperation research programme
(DLO-IC), the Dutch Ministry of Agriculture, Nature and Food Quality (LNV),
asked a small group of scientists to draw lessons from its recently completed North-
The limited available evidence favors the hypothesis that policy and prevalence of cannabis use are not strongly connected. However, there is hardly any literature focusing on the consequences of cannabis policy as implemented