Supervisors v. Kennicott was a United States Supreme Court case that addressed the issue of whether a state could tax the income of a federal employee. The case involved a dispute between the supervisors of the District of Columbia and the collector of taxes, John Kennicott. The supervisors argued that the District of Columbia was not subject to the taxation of the federal government and that the taxation of the income of a federal employee was unconstitutional. The Supreme Court disagreed and held that the taxation of the income of a federal employee was constitutional. The Court reasoned that the taxation of the income of a federal employee was necessary to ensure that the federal government was able to pay its employees and to ensure that the federal government was able to pay its debts. The Court also held that the taxation of the income of a federal employee was not a violation of the Constitution because the taxation was not a direct tax on the federal government. The Court concluded that the taxation of the income of a federal employee was a valid exercise of the taxing power of the state.

Justice Field delivered the dissenting opinion in Supervisors v. Kennicott, arguing that the majority's decision was contrary to both precedent and logic. He argued that a tax imposed on an occupation or profession is not a direct tax within the meaning of Article I, Section 2 of the Constitution because it does not fall upon property but rather upon persons who exercise their right to pursue certain occupations or professions. Furthermore, he noted that if such taxes were considered direct taxes then they would be subject to apportionment among states according to population which would make them practically impossible for Congress to impose due its complexity and difficulty in enforcement. Justice Field concluded by stating his belief that this type of taxation should be left up to state legislatures as long as it did not interfere with any rights secured under federal law.