Congressional Research Service 2
jurisprudence, would likely have been asserted as a substantive due process right. Less than two decades
later, in Zucht v. King, parents of a child who was excluded from school due to her unvaccinated status
challenged the local ordinance requiring vaccinations for schoolchildren, arguing that the ordinance
violated the Equal Protection and Due Process Clauses of the Fourteenth Amendment. Relying on
Jacobson, the Supreme Court rejected the constitutional challenges, concluding that “it is within the
police power of a State to provide for compulsory vaccination” and that the ordinance did not bestow
“arbitrary power, but only that broad discretion required for the protection of the public health.”
All 50 states, as well as the District of Columbia, currently have laws requiring specified vaccines for
students. This requirement is generally subject to certain exemptions, which vary from state to state.
While all student immunization laws grant exemptions to children for medical reasons (e.g., if a child is
allergic to vaccines or immunocompromised), most but not all states grant religious exemptions for those
whose beliefs counsel against immunization. Sixteen states also provide a broader philosophical
exemption for those who object to immunizations because of personal, moral, or other beliefs. While
compulsory vaccination requirements have faced legal challenges since Jacobsen and Zucht, courts have
consistently rejected these challenges and given considerable deference to the use of the states’ police
power to require immunizations to protect the public health. A number of relatively recent decisions, for
instance, have concluded that a state is not constitutionally required to provide a religious exemption,
upholding compulsory vaccination laws that provide only a medical exemption. In states that provide a
religious exemption and where parents have filed suit to challenge their unsuccessful invocation of the
exemption, courts, applying the relevant state law, have, at times, scrutinized whether their objections to
vaccination are based on a sincere religious belief.
Federal Authority Over Vaccination
Although states have traditionally exercised the bulk of authority in this area, Congress, as a result of
various enumerated powers in the Constitution, likewise has some authority over public health matters,
including regulation of vaccination. This authority derives from, among other sources, the Commerce
Clause and the Spending Clause of the U.S. Constitution. The Commerce Clause grants Congress the
power “[t]o regulate Commerce with foreign Nations, and among the several States.” This authority
empowers Congress to regulate “three broad categories of activities”: (1) “channels of interstate
commerce,” like roads and canals; (2) “persons or things in interstate commerce,” and (3) activities that
substantially affect interstate commerce. The Spending Clause empowers Congress to tax and spend for
the general welfare. Under this authority, Congress may offer federal funds to nonfederal entities and
prescribe the terms and conditions under which the funds are accepted and used by recipients. This power
is generally expansive, but the funding conditions on grants to the states are subject to certain limitations,
including that they must be germane to the federal interest in the particular national projects or programs
to which the money is directed.
Congress’s exercise of these authorities is also subject to certain external constraints. In the context of
public health regulations, the key constraints are those grounded in federalism and the protection of
individual rights. Pursuant to the principles of federalism, the Supreme Court has interpreted the Tenth
Amendment to prevent the federal government from commandeering or requiring state officers to carry
out federal directives. In the context of vaccination, this principle prevents Congress from requiring states
or localities to pass mandatory vaccination laws, but it does not impede Congress from using its Spending
Clause authority to provide incentives (in the form of federal grants) to states to enact laws concerning
vaccination. In terms of protection of individual rights, there are few external constraints on Congress’s
ability to impose mandatory vaccination requirements. Potential due process and equal protection
concerns, as noted above, are limited under Jacobsen and Zucht. Moreover, while the First Amendment’s
Free Exercise Clause seemingly could provide a limit on the federal government’s ability to require
vaccinations for those who would otherwise refuse on religious grounds, this constitutional concern is