The seriousness of a drug offense is determined by the quantity of drugs involved, whether the drug offense involved sale or mere possession, and also the type of drugs involved. Drugs are classified by schedules, ranging from the most serious (Schedule I), to the least serious (Schedule V).

Schedule I drugs are those having a high potential for abuse and for which there is no medical use in the United States. MDMA (ecstasy), LSD, and mescaline are several drugs classified as Schedule I.

Schedule II drugs also have a high potential for abuse, but do have a currently accepted medical use in the United States. Opium and opiums derivatives, along with cocaine and methamphetamine, are classified as Schedule II.

Schedule III drugs have a potential for abuse less than Schedule I and II drugs, and have currently accepted medical use in the United States. Some examples of drugs classified as Schedule III are Schedule IV drugs have a low potential for abuse and are frequently used for medical treatment. Among Schedule IV drugs are many drugs prescribed for anxiety such as diazepam (valium) and alprazolam (xanax).