Emerson College and Smith College on Wednesday became the latest Massachusetts colleges to announce that they would require all students to be vaccinated against COVID-19 before returning to campus this fall. Northeastern had already made a similar announcement, followed by Boston University. Others are likely to come.

Not everyone will follow suit. The Boston Globe reported April 6 that several colleges are encouraging vaccinations but not requiring it. Other schools have not yet made that decision. Some are making it easier for students to get vaccines – Brandeis announced last week that it had obtained 1,200 Pfizer doses to give students living in residence halls.

Education is the first industry to openly discuss mandating vaccines – which makes sense since schools have a fair amount of authority over their students, and colleges are populated by young adults who are often living and partying together.

Other industries are also considering mandating vaccinations, but it’s less simple for working adults. The Boston Business Journal reported that employer mandates fall into a legal gray area. While hospitals have a history of mandating vaccines like the flu shot for their staff, no one has ever dealt with the ramifications of mandating a vaccine like the COVID shots that only have FDA authorization for emergency use.

Some employers would have to negotiate vaccine requirements with unions. Businesses would also have to consider exemptions for disability, medical conditions, or religious beliefs to avoid running afoul of disability and religious accommodation laws. And employers generally have to be legally careful in asking employees about medical issues. The BBJ story found that many businesses are strongly encouraging employees to get vaccinated or offering incentives, but are not requiring it. The flip side, however, is businesses might also face legal liability if an unvaccinated worker passes on COVID-19 in the workplace.

So far, Gov. Charlie Baker has been unwilling to talk about the possibility of statewide vaccine passports in Massachusetts, which could allow only vaccinated people to participate in certain activities. The Biden administration has said it does not anticipate creating a national vaccine credential, although it is working on developing standards for people to prove they have been vaccinated, which could make it easier for private industries to require it.

Israel, which has the world’s highest vaccination rate, has already implemented a system of vaccine passports. BBC reported that the European Union is considering developing one.

The concept raises major questions about civil liberties and inequality, not to mention international travel.

Interestingly, Massachusetts paved the historical path for mandatory vaccinations. The first law allowing local boards of health to mandate a vaccine – at the time against smallpox – was enacted here in 1809. The first city to require a vaccine to attend public schools was Boston, which began requiring the smallpox shot in 1827. A case challenging Cambridge’s mandatory vaccine ordinance resulted in a 1905 US Supreme Court decision upholding the law, Jacobson v. Massachusetts, which remains the landmark case law on the issue today.