In the United States v. Behrman case of 1921, Dr. Samuel H. Behrman was convicted for unlawfully distributing a derivative of opium to an addict without a written prescription in violation of the Harrison Narcotic Act (1914). The Supreme Court upheld his conviction, rejecting his defense that he had prescribed the drug as part of a treatment plan for addiction and thus did not violate any law. The court ruled that prescribing narcotics to an addict merely to maintain their customary use does not constitute legitimate medical practice under the terms set by the Harrison Act; rather it is considered as contributing towards maintaining or increasing their addiction which is illegal according to this act.

In the dissenting opinion for United States v. Behrman, Justice McReynolds disagreed with the majority's interpretation of the Harrison Narcotic Act. He argued that Dr. Behrman was not selling drugs but prescribing them as a physician to an addict under his care, which he believed should be protected by law and professional discretion rather than criminalized. According to him, it is unreasonable to expect physicians to determine whether their prescriptions would maintain or cure addiction; such decisions are complex medical judgments beyond legal scrutiny. Thus, he contended that punishing doctors for making these difficult decisions could deter them from treating addicts altogether out of fear of prosecution - a consequence contrary to public health interests and legislative intent behind regulating narcotics through medical professionals in the first place.