In Jacobson v. Massachusetts, 197 U.S. 11, the U.S. Supreme Court ruled on Feb. 20, 1905, that a Massachusetts statute requiring smallpox vaccination was legal and appropriate. Supreme Court Justice John Marshall Harlan, delivering the opinion of the court, with two dissenting opinions, wrote that the police power of the state was paramount during an epidemic.

The legislature of Massachusetts required vaccination of its inhabitants and set appropriate penalties for refusal. The objection was predicated upon the Fourteenth Amendment to the Constitution.