197 U.S. 11 (1905) (U.S. Supreme Court)
Jacobson v. Massachusetts is the foundational U.S.
Does a state statute authorizing compulsory smallpox vaccination, enforced by a monetary penalty, violate the liberty interests protected by the Fourteenth Amendment's Due Process Clause?
Under the state's inherent police power, reasonable regulations that protect public health and safety may restrict individual liberty. A public health measure will be upheld if it bears a real and substantial relation to the protection of public health and is not, beyond all question, a plain, palpable invasion of rights. Courts may set aside measures that are arbitrary, oppressive, or have no reasonable relation to the public health objective, and as-applied relief may be warranted if enforcement would be cruel or dangerous for a particular individual medically unfit for the intervention.
The compulsory vaccination law, as applied, is a valid exercise of the state's police power and does not violate the Fourteenth Amendment. Jacobson's conviction and $5 fine were affirmed.
Jacobson establishes the constitutional baseline for evaluating public health regulations: the state may impose reasonable, non-arbitrary measures that bear a substantial relation to protecting community health. The decision is a touchstone for vaccination mandates, quarantine, and emergency responses. It has been invoked to support school-entry vaccination requirements (e.g., Zucht v. King) and, controversially, was cited in Buck v. Bell. Modern jurisprudence adds layers—such as heightened scrutiny for certain fundamental rights and First Amendment claims—so Jacobson is not a blank check. Still, its core teaching—that in the face of genuine public dangers, individual liberties can be reasonably curtailed—remains foundational in constitutional law and public health policy.