Social-media stocks have taken a beating this year, but it’s nothing compared with the smack-down their companies have recently received in court. “We reject the idea that corporations have a freewheeling First Amendment right to censor what people say,” the Fifth U.S. Circuit Court of Appeals declared in its Sept. 16 decision upholding Texas’s anticensorship law.

Social-media companies are also asking the justices to provide desperately needed constitutional clarity. They argue, in short, that removing user content from their platforms is an exercise of editorial judgment and expression protected by the First Amendment. Ergo, states can’t tell them they can’t censor.

Not so fast, writes the Fifth Circuit’s Judge Andrew Oldham for a divided three-judge panel in an excoriating 90-page opinion. Texas’ law prohibits large social-media platforms from blocking speech based on viewpoint. So users couldn’t be deplatformed by Twitter for professing skepticism of vaccines or climate change. Nor could YouTube demonetize such videos.

The law, however, excludes speech that isn’t protected by the First Amendment, such as incitement, as well as speech that is covered by Section 230 of the Communications Decency Act—i.e., speech considered to be “obscene, lewd, lascivious, filthy, excessively violent, harassing, or otherwise objectionable.”

Users who believe they were illegally discriminated against could sue the companies. While they wouldn’t be eligible to receive damages, they could be reinstated if they prevail. Many users would nonetheless lose if a court determines their expression is “objectionable” under Section 230’s catchall. But social-media companies wouldn’t be the final arbiters of what is objectionable.

Judge Oldham stresses that Texas’ law seeks to regulates business conduct—not speech—under the “common-carrier doctrine,” which holds that government can impose nondiscrimination obligations on businesses “affected with the public interest.” During the 19th century, states imposed common-carrier obligations on telegraph companies. “Western Union, the largest telegraph company, sometimes refused to carry messages from journalists that competed with its ally, the Associated Press—or charged them exorbitant rates,” Judge Oldham notes.

States, and later Congress, intervened to prohibit telegraph companies from discriminating against dispatches. The Supreme Court in 1896 rejected a constitutional challenge to a state common-carrier law.

Justice Clarence Thomas last year wrote that “the long history in this country and in England of restricting the exclusion right of common carriers and places of public accommodation may save similar regulations today from triggering heightened scrutiny” under the First Amendment, “especially where a restriction would not prohibit the company from speaking or force the company to endorse the speech.” Texas’ law does neither.

The Fifth Circuit cites two high-courts precedents that support the constitutionality of Texas’s law. In PruneYard Shopping Center v. Robins (1980) a mall challenged a California law that required privately owned shopping centers to permit the distribution of pamphlets on their premises. The mall argued that a “private property owner has a First Amendment right not to be forced by the State to use his property as a forum for the speech of others.” The court disagreed.

More recently, law schools in Rumsfeld v. Forum for Academic and Institutional Rights (2006) challenged a federal law that denied funding to schools that didn’t give military recruiters “access to students that is at least equal in quality and scope to the access provided other potential employers.” The court unanimously held the law didn’t violate the schools’ speech rights.

Social-media companies cite Miami Herald v. Tornillo (1974), which struck down a Florida law requiring newspapers to print candidates’ rejoinders to critical editorials. But in asserting a right to editorial control, they’re trying to have it both ways. As Judge Oldham notes, “they’ve told courts—over and over again—that they simply ‘serv[e] as conduits for other parties’ speech.’ ”

Newspapers and broadcasters exercise strict control over the content they promulgate and are legally liable for defamation. Social-media platforms don’t and aren’t. Section 230, in protecting platforms’ right to block and screen objectionable material, specifies that they shall not “be treated as the publisher or speaker” of content generated by users.

Social-media companies want to be able to censor speech they don’t like without bearing legal risks and responsibilities attendant to being a publisher. But why should courts let them?

Judge Oldman points out that Texas’ law differs from Florida’s in a few key respects that may make the latter more legally vulnerable. For one, Florida’s law specifically prohibits platforms from censoring candidates for public office or content about them as well as “journalistic enterprises.” This content-based regulation could trigger heightened First Amendment scrutiny.

Both Texas and Florida laws are innovative solutions to tech censorship, and they may not get it entirely right. But state laboratories of democracy are meant for experimentation.