489 U.S. 803 (1989)
Davis v. Michigan Department of Treasury is a landmark United States Supreme Court case that examines the issue of tax discrimination against federal retirees.
Does the Michigan tax exemption statute, which discriminates against federal retirees by exempting only state and local government retirees, violate the doctrine of intergovernmental tax immunity as codified in the Public Salary Tax Act of 1939?
Under the doctrine of intergovernmental tax immunity, as reinforced by the Public Salary Tax Act of 1939, states are prohibited from discriminating against federal employees in taxation matters compared to state employees.
The Supreme Court held that Michigan's tax scheme violated the constitutional principle of intergovernmental tax immunity. The statute discriminated against federal retirees by imposing differential taxation compared to state retirees, which the court deemed unconstitutional.
This case is pivotal in its reinforcement of the intergovernmental tax immunity doctrine, setting a precedent shielding federal retirees from state tax discrimination. It underscores the Court's commitment to maintaining equitable treatment between federal and state retirees within states' taxation policies. The decision also highlights the importance of federalism and the balance of power by ensuring federal employees are not disadvantaged by state policies.