Erin Miller (University of Southern California Law School) has posted Quasi-State Agents in First Amendment Doctrine on SSRN. Here is the abstract:
This article challenges the orthodoxy that First Amendment speech rights can bind only the state. I argue that the primary justification for the freedom of speech is to protect fundamental interests like autonomy, democracy, and knowledge from the kind of extraordinary power over speech available to the state. If so, this justification applies with nearly equal force to any private agents with power over speech rivaling that of the state. Such a class of private agents, which I call quasi-state agents, turns out to be a live possibility once we recognize that state power is more limited than it seems and can be broken down into multiple, equally threatening parts. Quasi-state agents might include a limited set of corporations, from the largest social media platforms to powerful private employers. However, because quasi-state agents are not exactly like state agents, but pursue important private aims that the state cannot, I argue that the First Amendment might bind them slightly differently (and less demandingly) than it does the state. Drawing on examples from American state and comparative constitutional law, I offer several analytical models for understanding this differential application.
And from the paper:
The First Amendment explicitly forbids only “Congress” from abridging the freedom of speech. But judicial interpretation has implicitly expanded the category of duty-holders to all state agents. Their justification: that these agents, like Congress, have power to impinge on the core First Amendment values, including the integrity of the democratic process, the pursuit of collective knowledge, and the autonomy of individual speakers. Therefore, for the theoretical coherence of the doctrine, a further expansion is required, to bind all agents—public or private—with similar powers to impinge on these values. Indeed, the Supreme Court seemed to recognize the same in a series of cases from the 1940s, 1950s, and 1960s— including the famous Marsh v. Alabama,6 which is gaining renewed attention in scholarship7— before veering course.
There other alternative would be to restrict the First Amendment to Congress. As applied to the states, the question is different. From an originalist perspective, the relevant provision is the Privileges or Immunities Clause and its relationship to the enumerated rights.
Highly recommended.