A ban on some foreign tourists is now in force in coffee shops in the Dutch border city of Maastricht, where cannabis is sold.
City authorities say an influx of tourists buying soft drugs is threatening public order and causing major traffic problems.
Coffee shop owners say the ban won't work and will hit the economy there.
However, the ban does not apply to visitors from Germany and Belgium who are the majority of foreign customers.
A proposed nationwide crackdown is being discussed in the Dutch parliament.
The BBC says the ban is being seen as a test case that could be implemented in other towns and cities.
The European Court of Justice ruled last December that foreigners can be barred from coffee shops selling cannabis.
There are about 700 coffee shops in the Netherlands. An estimated 6000 people visit Maastricht's coffee shops every day - mostly from Belgium and Germany.
From Saturday, anyone who does not hold a Dutch, Belgian or German passport will be told to leave.
Hi-tech security scanners have been set up to check passports and ID cards. Police will carry out random checks.
The Association of Official Coffee Shops Maastricht says visitors attracted by the coffee shops also spend an estimated 140 million euros (£120 million) elsewhere in the city every year.
