Earlier this month, a parent asked a question on the community-discussion listserv for the Cambridge, Massachusetts, school district where my teen-ager will start high school this fall. Since the state routinely requires students to have certain vaccinations for enrolling in public school, would it also require vaccination against COVID-19, once the F.D.A. moved the authorization status from “emergency use” to full approval? Other parents replied that they supported a requirement, predictably invoking science, public health, and communal values. But the vehemence of their opponents, in highly vaccinated Cambridge, took me by surprise. There were recriminations about interference with personal choice and references to Nazi Germany. One participant accused another of bullying and threatened to consult an attorney.

On Monday, the F.D.A. did grant full approval to the Pfizer-BioNTech coronavirus vaccine for people sixteen and older, and a decision on the Moderna vaccine is likely to follow in weeks, raising the question of how far and wide the government will now push COVID-vaccine mandates. In July, the Department of Veterans Affairs became the first federal agency to require some of its employees to get the vaccine or face possible termination. President Biden recently ordered all federal workers to attest that they are vaccinated or else wear masks and get tested weekly. Within hours of the F.D.A.’s full approval of the Pfizer vaccine, the Defense Department announced that it would mandate that all 1.4 million active-duty military members be vaccinated. On the same day, public university systems in New York, Minnesota, and Louisiana rolled out similar requirements for students. Such mandates may be met with intense resistance: the Pentagon’s pre-F.D.A.-approval vaccination efforts, for example, were highly divisive, and more than a third of service members are, at present, not fully vaccinated.

Strong resistance to government-mandated vaccination isn’t new. In 1853, Britain imposed the first mandatory vaccinations, requiring parents to inoculate infant children against smallpox or face heavy fines. Violent riots broke out, fuelling a national anti-vaccination movement that supported political candidates solely based on their stance on vaccination. In the late eighteen-nineties, some penalties were eliminated and conscientious objectors were allowed exemptions. But, by the mid-twentieth century, too many people—nearly half the population in some areas—were claiming exemptions, and the vaccination mandate was repealed altogether. Britain then dealt with outbreaks by other means, such as compulsory examination.

In the United States, there were few riots, but there were lawsuits. The most important case came out of Cambridge, in 1905. The Supreme Court considered a Massachusetts law that empowered cities’ boards of health to mandate vaccination of all residents if they found it “necessary for the public health or safety.” After an outbreak of a virulent strain of smallpox, the Cambridge board determined that vaccination was “necessary for the speedy extermination of the disease” and required all residents to receive the vaccine. A pastor from Sweden, who claimed that he had been made sick by a vaccine as a child, refused and was criminally convicted and fined. He challenged the law as a violation of due process, arguing that compulsory vaccination was “hostile to the inherent right of every freeman to care for his own body and health in such way as to him seems best, and . . . nothing short of an assault upon his person.”

The Court, in Jacobson v. Massachusetts, disagreed, reciting the principle that individual liberty is not absolute in the face of “the common good,” and that “real liberty for all” depends on restraining individual exercises of liberty that harm others. The Court, as Justice John Marshall Harlan wrote, was therefore “unwilling to hold it to be an element in the liberty secured by the Constitution of the United States that one person, or a minority of persons, residing in any community and enjoying the benefits of its local government, should have the power thus to dominate the majority” that acts through the state’s authority to protect health and safety. The Court therefore held that a state had legal authority to require vaccinations. Seventeen years later, it also held that neither due process nor equal protection prohibited a San Antonio ordinance making vaccination a condition of children’s attendance in schools.

Since the nineteen-eighties, all fifty states have required vaccinations for school attendance, subject to some exemptions, including on medical and religious grounds. Vaccination requirements have long been challenged by religious objectors, but the challenges are routinely rejected, as long as reasonable accommodations are offered. Just last year, the Fifth Circuit heard the case of a former firefighter who had religious objections to a vaccine for tetanus, diphtheria, and whooping cough that was required for his job, and who was fired when he rejected accommodations that the city offered: to transfer to a job that didn’t require the vaccine, or to wear a respirator mask at work. The court rebuffed the employee’s claims of religious discrimination and violation of First Amendment free-exercise rights. The pre-COVID legal landscape, in other words, was quite clear: a state could require vaccinations to protect public health, even imposing criminal penalties for noncompliance. And vaccination as a condition of attending school or of government employment has been widely, if not universally, accepted.

There has been a plethora of legal challenges to COVID-vaccine mandates imposed by public and private institutions, but courts have been quick to dismiss them. This summer, eight students sued Indiana University over its policy that all students must be vaccinated against the coronavirus unless they are exempt for religious or medical reasons. (Most student plaintiffs claimed exemptions, but still objected to the school’s requirement that exempt students wear masks and be tested twice a week.) The Seventh Circuit appeared to find it easy to determine that, in light of Jacobson, “there can’t be a constitutional problem” with requiring vaccination against COVID-19. Noting that “vaccinations against other diseases (measles, mumps, rubella, diphtheria, tetanus, pertussis, varicella, meningitis, influenza, and more) are common requirements of higher education,” the court was unsympathetic to the students’ complaints, given that they could choose to go to a school that doesn’t require the COVID vaccine, and that masks and tests for exempt students are “requirements that are not constitutionally problematic.” When the students then asked the Supreme Court for an emergency stay to block the university’s policy, Justice Amy Coney Barrett simply denied it, without referring it to the full Court, perhaps indicating a lack of interest in reconsidering Jacobson in the COVID era.

No city or state has yet issued a straight-up requirement that all private citizens be vaccinated against COVID-19, along the lines of the Massachusetts smallpox-vaccination law upheld in Jacobson, but some have edged toward it. The closest so far is New York City’s requirement of proof of having received at least one dose for access to certain activities, including indoor dining, gyms, and performances. Various states have also ordered certain subsets of their populations, including health-care and nursing-home workers, school teachers, and state employees, to be vaccinated or face regular testing. The F.D.A.’s full approval of the vaccine this week makes it more likely that cities and states will impose general mandates on residents. If they do, they can feel confident that such requirements will be upheld by the courts, so long as they include medical and religious exemptions.

If, as seems probable, we see an increasingly dense and complicated patchwork of mandates emerge over the coming months, some might wonder about the possibility of a federal vaccination requirement. Beyond mandating inoculation of federal employees, the Biden Administration has pressured non-federal institutions to require vaccination, using the carrot of federal funding (or the stick of its potential withdrawal). As a condition of continuing to receive federal funding, the Administration has directed all nursing homes to require their staff to be vaccinated. Last week, Biden rebuked states that blocked schools from adopting mask requirements, and the Education Department suggested that infringing on school districts’ authority to adopt policies for safely returning to schools could result in withdrawal of federal funding. It is possible that the Administration could use a similar threat to prevent states from blocking school districts’ vaccine requirements.