Kailing v. United States

John Kailing, a devout Catholic, challenged a federal COVID-19 vaccine mandate requiring proof of vaccination for interstate air travel. He argued that the mandate forced him to violate his sincere religious beliefs because the available vaccines were developed or tested using fetal cell lines derived from abortions. After lower courts upheld the mandate, the Supreme Court granted certiorari. On March 31, 2026, the Court examined whether the blanket denial of religious exemptions imposed a substantial burden on religious exercise under the Religious Freedom Restoration Act (RFRA) and whether the government demonstrated that a uniform mandate without exemptions was the least restrictive means of advancing a compelling public health interest. The case placed the limits of emergency executive power against robust First Amendment protections, drawing intense national attention.

In a 6-3 decision, the Supreme Court ruled in favor of Kailing, holding that the government failed to prove that refusing all religious accommodations was the least restrictive means to achieve its compelling interest in public health. The mandate was struck down as applied to individuals with sincere religious objections, and the government was ordered to implement a meaningful exemption process.

Whether a federal vaccine mandate for interstate travel that provides no religious exemptions violates the Religious Freedom Restoration Act and the Free Exercise Clause of the First Amendment.

The ruling significantly curtailed the federal government’s ability to impose uniform vaccine mandates without religious accommodations, leading to revised public health policies across multiple agencies. It intensified the national debate over the scope of emergency powers and reaffirmed strong protections for religious liberty, setting a precedent that influenced subsequent challenges to workplace, school, and healthcare mandates nationwide.