How are controlled substances defined?

Controlled substances are defined as drugs that are regulated by law due to their potential for abuse and dependence. This classification occurs because certain substances can lead to severe psychological or physical dependence when misused. The legal framework surrounding these substances includes stringent guidelines for their manufacture, distribution, and prescribing.

For example, the Controlled Substances Act (CSA) categorizes drugs into schedules based on their potential for abuse, medical usefulness, and safety. Schedule I substances, like heroin, have a high abuse potential and no accepted medical use, while Schedule II substances, like morphine, are recognized for medical use but still carry a high risk of abuse.

While the other options touch upon aspects of controlled substances, they either oversimplify the definition or focus on specific characteristics that do not encompass the full legal context.