The Volokh Conspiracy
Mostly law professors | Sometimes contrarian | Often libertarian | Always independent
Say the government outright forbids handshaking, on the theory that it needlessly risks spreading illness (illness that, whether for COVID-19 or for ordinary cold and flu, creates some risk of death for some third parties). I think this would be needless overkill; even if handshaking is dangerous to public health, and persists just because it's a custom that's socially hard for people to break, it seems to me that social pressure (perhaps supported by recommendations by a cross-the-aisle coalition of government officials) is a much better solution to that problem than outright prohibition. Still, say the government institutes such a ban; would it be constitutional?
[1.] The First Amendment: A handshake is a classic form of symbolic expression; the message it sends ("I greet you cordially") isn't as political as the message involved in past symbolic expression cases (such as waving a flag, saluting a flag, burning a flag, or wearing a black armband to protest the Vietnam War), but it's still covered by the First Amendment.
Nonetheless, a handshaking ban would be a classic example of a restriction on symbolic expression that is justified by the noncommunicative impact of the expression—it's not about the message, but rather about the risk that the conduct transmits germs entirely without regard to the message. Such restrictions are treated much like content-neutral speech restrictions, and are generally constitutional so long as they pass a pretty government-friendly form of so-called "intermediate scrutiny": The government has to show that they help materially advance an important government interest. (See United States v. O'Brien.) If the government can show that the restriction will tend to reduce transmission of illness, or likely even if the medical evidence is unclear but the restriction seems likely to do that, then intermediate scrutiny will be satisfied.
[2.] The right to intimate association: You have a right to choose your friends, likely your roommates, fellow members of small, selective clubs, and the like. (Your right to choose your lovers, see Lawrence v. Texas, may be seen as a facet of this same right.) But restrictions on handshakes, even with friends, are unlikely to be seen as a "substantial burden" on the right.
[3.] The right to do what one wants with one's body: The Court has never recognized a general right to use one's body as one likes; outside some specifically recognized rights, such as rights of intimate association, sexual autonomy, or freedom from unwanted intrusive medical treatment, any restriction would only need to be rationally related to a legitimate government interest. This one would surely qualify. (Note that sometimes the government can even command intrusive medical treatments, such as with mandatory vaccination rules; but those may require some substantial showing of public health necessity, and I'm inclined to say that handshaking bans would require a lesser showing.)
[4.] Federal power: So far, what I've said applies to state and local restrictions; if the federal government wanted to impose such a ban, the ban would not only need to comply with the Bill of Rights, but would also have to be within the federal government's enumerated powers. Handshaking isn't commercial activity, nor would a handshaking ban be part of an overall scheme for regulating commerce, so it can't be directly regulated under the Commerce Clause (see United States v. Lopez and Gonzalez v. Raich). It might be restrictable, though, on the theory that such a restriction is "necessary and proper" to "regulate commerce … among the several states," since people who are infected in one state can easily move into another. (Travel of people is viewed as interstate "commerce," see Edwards v. California.)
[5.] Government as employer, educator, and the like: All that I've said above involves the government acting as sovereign, restricting (through criminal or civil penalties) handshaking even by private people in privately owned places. The government as employer, educator, and the like would likely have much greater authority. In particular, the federal government could certainly impose such a restriction on federal property and in federal workplaces.
Again, an outright governmental ban on handshaking strikes me as a poor idea. But it likely would be constitutionally permissible, at least when imposed by state governments, and possibly even when imposed by the federal government. And even much greater restraints on liberty (such as vaccinations or quarantines) are often allowed when infectious disease is involved.