Considered THE archetypal sensationalized anti-drug movie, but it's really an exploitation film made to capitalize on the hot taboo subject of marijuana use. Like many exploitation films of the time, "Reefer Madness" tried to make a quick buck off of a forbidden subject while skirting the Motion Picture Production Code of 1930. The Code forbade the portrayal of immoral acts like drug use. ( The illegal drug traffic must not be portrayed in such a way as to stimulate curiosity concerning the use of, or traffic in, such drugs; nor shall scenes be approved which show the use of illegal drugs, or
You can stream Reefer Madness (1938) free and legally on OldReel, via the Internet Archive.
Yes — it is in the public domain and can be watched and shared freely.