Yes, there are laws against public drug use in the Netherlands. The Dutch Opium Act prohibits the possession, sale, cultivation, and use of certain drugs in public places. The substances covered by this law include cannabis, cocaine, heroin, and psychedelics. Possession of these substances is punishable by law and can result in imprisonment. The possession of small amounts of cannabis is tolerated in the Netherlands, but it is still illegal to consume cannabis in public places.

Additionally, it is illegal to sell, possess, or use drugs in places where the public has access and where there is a risk of public disturbance. This includes parks and city squares. The police can detain anyone they suspect of using or selling drugs in public.

Overall, it is important to remember that public drug use is illegal in the Netherlands. Violations of these laws can result in serious penalties, including imprisonment. It is best to consume drugs in private, or with permission from the property owner, if it is legal to do so.