"The Dutch harm reduction policy postulates a distinction between drugs with acceptable and unacceptable health risks. This policy is
laid down in the so-called ‘Opium Act’. The Opium Act of 1976 regulates the status of a large number of substances. The law has a dual listing of substances it declares as ‘illicit’ for use, production or distribution. Schedule I contains all the substance drugs with ‘unacceptable risks’ (including hash oil). Schedule II was created for cannabis products such as hashish and marijuana. Both categories are illicit, but priority for criminal investigation and prosecution is given to the first. Maximum penalties for trafficking drugs with ‘unacceptable risks’ were raised in 1976, and penalties for possession of cannabis for personal use in amounts up to 30 grams were lowered, with possession constituting a misdemeanour (Korf, 1995). In October 1996 this amount was revised to 5 grams for personal use, and 500 grams for coffee shop owners. At the same time, magic mushrooms were added to Schedule II. (Public Prosecution Service, regarding guidelines for criminal offences against the Opium Act1).

"Hashish and marihuana (cannabis) are drugs with acceptable risks and their sale is tolerated in coffee shops. Conditions are laid down by the government as well as by local policy-makers. Coffee shop owners can possess up to 500 grams. If they have more in stock or if they do not obey other regulations, the local police may intervene, depending on the nuisance caused and the local policy. The government has drawn up directives, which coffee shops have to follow in order to be tolerated. These rules are the Ahojg directives. They stand for: No advertising (A); No sale of hard drugs (although ‘hard drugs’ is not an official term, it is mentioned in the directives, referring to Schedule I drugs) (H); No nuisance (O); No sale of drugs to youths under 18 years of age and no admission of youths to coffee shops (J); No sale of large quantities (max 5 grams per transaction) (G)."

Source

Abraham, Manja D., University of Amsterdam, Centre for Drug Research, Places of Drug Purchase in The Netherlands, Amsterdam: University of Amsterdam, September 1999.