Controlled substances refer to drugs whose use and possession are regulated by law. The Controlled Substances Act of 1970 established five schedules to classify drugs based on their potential for abuse and accepted medical use. Schedule I drugs like heroin and psilocybin/psilocin have a high potential for abuse and no accepted medical use. Marijuana, cocaine, and opioids like morphine and codeine are derived from plants and have histories of medical and recreational use. Tobacco is a commercially grown plant that contains the addictive substance nicotine.