This factor is included in the Controlled Substances Act to allow the control of chemicals (like lysergic acid) and substances (like poppy straw) that are involved in the manufacture of controlled substances. The relationship of marijuana and its constituent parts is analogous to that of precursor chemicals. This is a good context for a discussion of the relationship of marijuana to its constituent parts.

The DEA maintains that studies involving THC or other cannabinoids are not a valid basis for scientific assertions about marijuana. The topic has been discussed above in section 2 on the pharmacology of marijuana. This section addresses this issue within the context of the practices and traditions of the scientific community, particularly in a historical context.