Illegal drugs (often referred to as “controlled substances”) in Massachusetts are divided into five different categories, or classes: A, B, C, D and E. Generally speaking, the controlled substances in classes A and B include addictive street drugs like heroin, amphetamines and cocaine, as well as oxycontin and LSD. They are the most strictly regulated, and convictions for possession or selling them carries the harshest sentences. Class C substances include some stimulants and depressants, pain killers, and many anesthetics and analgesics. Class D substances include marijuana, along with stimulants and depressants with lower abuse potential. Class E includes therapeutic drug mixtures containing limited quantities of controlled substances as well as prescription drugs not included in other classes.