Article L.3421-4 of the "Code de la Santé Publique" (law concerning public health) forbids incitation/encouragement of the usage or traffic of classified narcotics, even if it does not lead to anyone actually using them. The sentence is heaviest if it's done near schools. Isn't there something vaguely equivalent in US law?

The interesting part is that the act of presenting classified narcotics under a favorable light (in press for example) is punishable under the same article.

In some regards this is pretty vague, and I've seen government-funded studies that end up presenting cannabis "in a favorable light", so I'm not sure how much this is enforced.