ABSTRACT
What is a drug? A simple way to define a drug is as a substance that when ingested causes a physiological change. Aspirin is a drug but flour is not, even though both are frequently ingested. Drugs become a law enforcement issue when they are abused or lead to criminal behavior. The concept of drugs as legal or illegal is surprisingly new; it wasn’t until the 1970s that certain drugs were placed on lists of what were called controlled substances. In the 1960s, for example, LSD was legal.
