The Supreme Court of the United States ruled in Jacobson v. Massachusetts that states had the authority to order compulsory vaccination.

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.

Jacobson v. Massachusetts, 197 U.S. 11 (1905), was a United States Supreme Court case in which the Court upheld the authority of states to enforce compulsory vaccination laws. The Court's decision articulated the view that individual liberty is not absolute and is subject to the police power of the state. Jacobson has been invoked in numerous other Supreme Court cases as an example of a baseline exercise of the police power.

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.