In the United States v. Doremus case of 1918, the Supreme Court upheld a conviction under the Harrison Narcotics Tax Act of 1914. The defendant, David Doremus, was a physician who prescribed morphine to an addict not for treatment but simply to maintain their addiction. He argued that this act was unconstitutional as it overstepped Congress's power to tax and instead regulated medical practice - something reserved for states' rights under the Tenth Amendment. However, in its decision, the court held that while Congress cannot regulate medical practice directly within a state; it can enforce taxes leading indirectly towards regulation or prohibition if such enforcement is necessary for protecting revenue interests. Therefore, even though part of its effect may have been regulatory rather than related purely to taxation purposes alone; since there were legitimate tax-related aspects involved too (like requiring registration and payment), it did not violate any constitutional provisions.

In the dissenting opinion for United States v. Doremus, Justice McKenna argued that the Harrison Act was not a tax law but rather a regulatory measure aimed at suppressing drug addiction. He believed that Congress had overstepped its constitutional authority by using taxation as an excuse to regulate personal behavior and medical practice, areas traditionally left to state control. The majority's interpretation of the act as a revenue-raising measure was, in his view, incorrect because it ignored clear evidence of Congress' intent to use taxation as a means of controlling narcotics distribution and use. Furthermore, he contended that if such regulation were allowed under the guise of taxation then there would be no limit on federal power since any conduct could potentially be regulated through taxes.