Which schedule of controlled substances has the highest potential for abuse?

The correct answer is that Schedule I substances have the highest potential for abuse. Schedule I substances are defined as drugs that have no accepted medical use in the United States, are considered to have a high potential for abuse, and can lead to severe psychological or physical dependence. Because of these factors, they are strictly regulated and cannot be prescribed. Examples of Schedule I substances include heroin, LSD, and marijuana (at the federal level).

In contrast, Schedule II substances, while still having a high potential for abuse, are recognized for their medical uses but come with strict regulations regarding their prescription. Schedule III and Schedule IV substances are considered to have a lower potential for abuse compared to Schedule I and II substances, with Schedule IV having the least potential in this classification hierarchy. Thus, Schedule I clearly represents the category with the highest potential for abuse.