The study of eight cases of cannibalism committed by schizophrenic patients revealed that the victims are often people from the family circle. The authors of this crime develop clinically mystical or persecution delusions. Especially, in five cases, acting out has been made under the influence of psychoactive substances including four cases of cannabis use. The nature of the possible link between cannabis use and cannibalism among schizophrenic patients is studied. The legal implications of this link are analyzed. More generally, the social safety cannabis use is questioned.