How Trump’s own Supreme Court justice undercut his Facebook lawsuit

… When a private entity provides a forum for speech, the private entity is not ordinarily constrained by the First Amendment because the private entity is not a state actor. The private entity may thus exercise editorial discretion over the speech and speakers in the forum. This Court so ruled in its 1976 decision in Hudgens v. NLRB.

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Therefore, a private entity who provides a forum for speech is not transformed by that fact alone into a state actor. After all, private property owners and private lessees often open their property for speech.

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In short, merely hosting speech by others is not a traditional, exclusive public function and does not alone transform private entities into state actors subject to First Amendment constraints. If the rule were otherwise, all private property owners and private lessees who open their property for speech would be subject to First Amendment constraints and would lose the ability to exercise what they deem to be appropriate editorial discretion within that open forum.

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As the Court said in Hudgens, to hold that private property owners providing a forum for speech are constrained by the First Amendment would be “to create a court-made law wholly disregarding the constitutional basis on which private ownership of property rests in this country.”