COPENHAGEN — When a phalanx of Danish policemen in bulletproof vests crosses the boundary into Christiania Freetown, the hippie commune in the center of Copenhagen, many things happen at once.

There is urgent shouting. Lumps of hashish and bags of marijuana disappear into black vinyl sacks, which are then rolled up and thrown onto roofs, hidden under floorboards and stuffed into ingeniously camouflaged hidey-holes — inside hollow propane tanks or behind mirrors. The dealers themselves scatter, sneakers pounding.

By the time the police officers reach the open-air hash market on Pusher Street, pistols at their hips, the scent of hash has been replaced by the scent of cinnamon rolls, and half the population is missing. The police march through, poking ineffectually at the drug-dealers’ empty stalls.