"The cannabinoid receptors are a class of cell membrane receptors under the G protein-coupled receptor superfamily. As is typical of G protein-coupled receptors, the cannabinoid receptors contain seven transmembrane spanning domains. Cannabinoid receptors are activated by three major groups of ligands, endocannabinoids (produced by the mammalian body),
plant cannabinoids (such as THC, produced by the cannabis plant) and synthetic cannabinoids (such as HU-210). All of the endocannabinoids and plant cannabinoids are lipophilic, i.e. fat soluble, compounds."
http://en.wikipedia.org/wiki/Cannabinoid_receptors
People want to outlaw something that the human brain naturally functions with? lol