The United States Supreme Court upholds mandatory vaccinations for public school students in Zucht v. King.

The Supreme Court of the United States (SCOTUS) is the highest court in the federal judiciary of the United States. It has ultimate appellate jurisdiction over all U.S. federal court cases, and over state court cases that turn on questions of U.S. constitutional or federal law. It also has original jurisdiction over a narrow range of cases, specifically "all Cases affecting Ambassadors, other public Ministers and Consuls, and those in which a State shall be Party." In 1803, the court asserted itself the power of judicial review, the ability to invalidate a statute for violating a provision of the Constitution via the landmark case Marbury v. Madison. It is also able to strike down presidential directives for violating either the Constitution or statutory law.

A vaccination policy is a health policy adopted in order to prevent the spread of infectious disease. These policies are generally put into place by state or local governments, but may also be set by private facilities, such as workplaces or schools. Many policies have been developed and implemented since vaccines were first made widely available.

Zucht v. King, 260 U.S. 174 (1922), was a landmark decision by the Supreme Court of the United States in which the Court unanimously held that public schools could constitutionally exclude unvaccinated students from attending, even if there was not an ongoing outbreak. In the case, the school district of San Antonio, Texas enacted an ordinance that prohibited any child from attending a school within the district unless they had been vaccinated against smallpox. One parent of a student who had been excluded, Rosalyn Zucht, sued on the basis that there was not a public health emergency. Justice Louis Brandeis wrote for the unanimous court that requiring students to be vaccinated was a justified use of "police power" to maintain public health and safety.