21 U.S.C. Sec. 952(A) is the Definition of Controlled Substance. This section defines a controlled substance as any drug, substance, or chemical listed in Schedules I through V of the Controlled Substances Act. Schedule I substances are the most strictly regulated and have a high potential for abuse and no currently accepted medical use. Schedules II through V are substances that have accepted medical use but vary in their potential for abuse. Types of Schedule I controlled substances include opiates, hallucinogens, and certain stimulants. Types of Schedule II through V controlled substances include certain analgesics, tranquilizers, and stimulants.