Maastricht council has asked two researchers from Tilburg university and the COT Safety and Crisis Management Centre in Leiden to look into the effects of the cannabis pass.

The government wants to introduce the special passes for coffee shop users to limit marijuana use to local Dutch people and stamp out drugs-related violence.
The researchers will look at drugs-related problems in areas in South Limburg and along the Belgian border with no coffee shops, and then compare these findings with the nuisance caused in towns and cities with coffee shops.
The results are expected before the end of June.