This question came up because I read that Bolsonaro, Brazil's president, was criticized by the opposition for saying that COVID-19 vaccinations won't be mandatory. The opposition said that the vaccine should be a requirement, which means that if they were in power, then everyone in Brazil would be forced to get vaccinated.

Specifically for the United States, is it possible that getting vaccinated become a law? In other words, I would be breaking the law if I decide not to get vaccinated.

Is something like this remotely possible?

The reason I ask: countries are trying to develop a vaccine as fast as humanly possible and possibly trying to cut corners to have the vaccine approved. Superpowers like the US, Russia, and China are all making claims.

Here in the US, being an election year, the CDC is already saying that two unidentified vaccines will be available in October or November. I feel this is being done in a hurry, and I wouldn't want the government to force me to get vaccinated with a brand-new drug with limited testing.

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    Does it count if being unvaccinated is not illegal per se, but ever leaving your home unvaccinated is against the law?
    – Patrick87
    Commented Sep 5, 2020 at 15:52
  • Well, anything that negatively affects your well-being. If I can't leave the house, I can't work. If I can't work, I can't pay. If I can't pay... Commented Sep 6, 2020 at 15:19
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    While I agree with the sentiment, does a vaccine count as a "drug"? Commented Sep 7, 2020 at 18:50
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    @AzorAhai: Almost certainly yes, at least in terms of FDA regulation. It is an "article intended for use in the [...] prevention of disease" and thus falls within the scope of 21 USC 321(g)(1).
    – Kevin
    Commented Aug 17, 2021 at 19:54

2 Answers 2


It was decided back in 1905 in the case of Jacobson v Massachusetts, 197 U.S. 11, that mandatory vaccination laws are constitutional in the US (the specific example being mandatory smallpox vaccination - through vaccination, this illness was eradicated globally). The court observed that

in every well ordered society charged with the duty of conserving the safety of its members the rights of the individual in respect of his liberty may at times, under the pressure of great dangers, be subjected to such restraint, to be enforced by reasonable regulations, as the safety of the general public may demand. An American citizen, arriving at an American port on a vessel in which, during the voyage, there had been cases of yellow fever or Asiatic cholera, although apparently free from disease himself, may yet, in some circumstances, be held in quarantine against his will on board of such vessel or in a quarantine station until it be ascertained by inspection, conducted with due diligence, that the danger of the spread of the disease among the community at large has disappeared.

The power of the government to protect is not totally unfettered: its actions must be necessary.

Smallpox being prevalent and increasing at Cambridge, the court would usurp the functions of another branch of government if it adjudged, as matter of law, that the mode adopted under the sanction of the State, to protect the people at large was arbitrary and not justified by the necessities of the case. We say necessities of the case because it might be that an acknowledged power of a local community to protect itself against an epidemic threatening the safety of all, might be exercised in particular circumstances and in reference to particular persons in such an arbitrary, unreasonable manner, or might go so far beyond what was reasonably required for the safety of the public, as to authorize or compel the courts to interfere for the protection of such persons.

An attack on a mandatory vaccination law would probably focus on the question of necessity.

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    I would also focus that on the safety of the vaccine itself. Smallpox vaccines have decades of testing, while there will be enough of uncertainty on COVID-19 ones as they get out.
    – Ángel
    Commented Sep 6, 2020 at 2:10
  • The first quote doesn't directly mention mandatory vaccination, although it does mention mandatory quarantine. I suppose it wouldn't be impossible to have different groups of people debating its applicability.
    – user8913
    Commented Sep 6, 2020 at 2:55
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    @Panzercrisis The case itself was about a mandatory vaccination. The quote is just posing a hypothetical that has a distinguishable fact pattern from the one at hand, but which lends itself to the same essential conclusion. Commented Sep 6, 2020 at 3:20
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    @zibadawatimmy Oh, I see. Thanks!
    – user8913
    Commented Sep 6, 2020 at 3:29
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    @Ángel And in turn, that would depend on the method of vaccine production. E.g. a novel technique vs a variant of a well tried method. Flu vaccines for example are different every year and therefore haven't been tested long term. But they are designed using methods which are well established.
    – JBentley
    Commented Sep 7, 2020 at 12:52

Yes. In its 1904 term, the Supreme Court upheld the constitutionality of a Massachusetts law requiring small pox vaccinations in Jacobson v. Massachusetts. The Court held that the law did not violate the 14th Amendment by depriving Jacobson of his "liberty" without "due process of law."

In upholding compulsory vaccination, the Court used the "police power" analysis that is standard in cases involving the due process clause. It held mandatory vaccination was a "reasonable" exercise of the "police power," the power to regulate for the "good and welfare of the Commonwealth." It added that "the legislature" was "primarily the judge" of when and how to use this power. Courts could only step and overturn a statute if it was so "arbitrary" and "unreasonable" as to be "oppressive." In reviewing legislative decisions about the police power, the court had to be mindful of the separation of powers. It was "no part" of the judicial "function" to worry about the "expediency" or effectiveness of a statute.

Here is how the majority described the police power:

in every well-ordered society charged with the duty of conserving the safety of its members the rights of the individual in respect of his liberty may at times, under the pressure of great, dangers, be subjected to such restraint, to be enforced by reasonable regulations, as the safety of the general public may demand

Here is how the Court dealt with the claim that these regulations were unconstitutional because they interfered with liberty:

the liberty secured by the Constitution of the United States to every person within its jurisdiction does not import an absolute right in each person to be, at all times and in all circumstances, wholly freed from restraint. There are manifold restraints to which every person is necessarily subject for the common good. On any other basis organized society could not exist with safety to its members. Society based on the rule that each one is a law unto himself would soon be confronted with disorder and anarchy.

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    missed the word term! Yes, the 1904 term but in 1905. which is confusing, yes. Though the term is often referred to under the 1905 date: "Jacobson v. Massachusetts, 197 U.S. 11 (1905)"
    – Trish
    Commented Sep 6, 2020 at 20:25
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    @Trish It is confusing! Unfortunately, there are two different ways of dating a decision: 1) Using the Term in which it was decided; 2) Using the Year in which the decision was announced. These methods usually give different years for a case. That's because few cases are decided early in the term. When using the Term, it is traditional to give both the year and the word "Term". The official citation, which you quote, gives the year the decision was announced, not the term in which it was announced.
    – Just a guy
    Commented Sep 6, 2020 at 21:16

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