The administrative process by which the scheduling of drugs and substances is reviewed and, if warranted by scientific evidence, changed is known as an administrative rule making procedure. Official reports on the status of any particular rule making procedure are published in the Federal Register.
FDA also concluded that abuse of the plant material may lead to severe psychological dependence in some individuals but that the information available was insufficient to determine with certainty whether the plant material produce physical dependence. 51 FR22947 (1986)
This admission should be contrasted with the language of the Controlled Substances Act which mandates that “a drug or other substance may not be placed in any schedule unless the findings required for such schedule are made with respect to such drug or other substance.” (21 USC 812 (b))A finding on abuse potential is required for Schedule I status. Either they have one on record, or they do not. Apparently the finding does not exist, and marijuana’s current schedule I status is based on a presumption that a finding will one day be established.