Marsh was the 1946 Supreme Court case which found that First Amendment protections for free speech can be applied to private sector actors in some circumstances. In the case, a company town owned by the Gulf Shipbuilding Corp. sought to bar free speech on its sidewalks, claiming that the First Amendment only proscribed government censorship, not private sector actions.
In a 5-3 decision authored by First Amendment champion Hugo Black, the high court disagreed, finding that when the private sector actor owns and controls the de facto “public square,” then Americans’ constitutional protections still apply.
In the context of free speech, the Internet social media sites are uniquely important, with an impact far beyond access to shopping malls. In a 2017 case, Packingham v. North Carolina, the court made clear that the Big Tech social media sites have become THE public square of our time, ruling unanimously that even convicted sex offenders cannot be blocked or censored from Facebook and Twitter.
As you may recall, you read this idea here first, when I argued two years ago that use as a public space diminishes the public/private distinction and allows First Amendment rights to extend to this space:
If we combine the view of these three cases, we see that a new form of law is evolving to deal with privately-owned entities that act as public forums. In other words, they do not need public ownership to serve a public role, and if they do, they have an obligation to uphold speech rights.
In fact, some of the oldest legal reasoning on the topic suggests that private spaces which act like public spaces are beholden to the same rules as actual public spaces:
The town, a suburb of Mobile, Alabama, known as Chickasaw, is owned by the Gulf Shipbuilding Corporation. Except for that it has all the characteristics of any other American town.
Ownership does not always mean absolute dominion. The more an owner, for his advantage, opens up his property for use by the public in general, the more do his rights become circumscribed by the statutory and constitutional rights of those who use it.
Since these facilities are built and operated primarily to benefit the public and since their operation is essentially a public function, it is subject to state regulation.
We do not think it makes any significant constitutional difference as to the relationship between the rights of the owner and those of the public that here the State, instead of permitting the corporation to operate a highway, permitted it to use its property as a town, operate a “business block” in the town and a street and sidewalk on that business block.
In other words, if it acts like a public space, it is a public space as far as Constitutional rights are concerned. The interesting argument here translates into the question, “If this business concern were to make itself a municipality, what rules would it be forced to obey?”
As far as I can tell, right now we simply lack attorneys and courts brave enough to acknowledge this clear legal precedent, just like we lack politicians with enough intestinal fortitude to repeal § 230 of the Telecommunications Act.