Responding to a petition on Monday, Supreme Court Justice Clarence Thomas laid out a comprehensive constitutional framework for regulating Twitter moderation, signaling that Thomas and other conservatives are eager to take action against social media platforms.

Thomas was writing in response to a case brought in 2017 by Columbia University’s Knight First Amendment Institute, arguing that President Trump was violating the First Amendment by blocking critics on Twitter. A federal appeals court ruled in favor of the institute in 2019 and Biden’s White House has declined to contest that ruling, making it pointless to continue the case. But since an appeal was filed while Trump was still president, the court is formally required to respond.

While the dismissal has little legal significance, Justice Thomas used the case as an opportunity to weigh in on more profound issues facing social media platforms. Thomas’ response focuses primarily on Twitter’s decision to ban Trump from the platform in the wake of the Capitol riot.

Nearly every major platform banned then-President Trump in the wake of the Capitol riot — including Facebook, YouTube, and Twitter — with most citing terms-of-service provisions against using the platform to incite violence. There has been no meaningful legal effort to contest the bans but they remain politically controversial, particularly among American conservatives.

While the ban took place more than six months after the appellate ruling in the Knight case, Thomas uses it as a pretext to examine the separate issue of how Congress or the courts could legally restrain Twitter’s moderation powers to prevent such bans in the future. Over 12 pages, Thomas draws out a detailed case for how lawmakers might restrain platform moderation without violating the First Amendment, drawing on both common carrier designations and English common law rules around the right to exclude customers from public accommodations.

Specifically, Thomas argues that lawmakers could use the scale and public nature of platforms like Twitter to justify new moderation rules, similar to the way the Telecommunications Act prevents phone companies from blocking specific people from phone service. Failing that, lawmakers could craft a statute similar to the public accommodations clause of the Civil Rights Act, which prevents hotels and restaurants from barring service on the basis of race or creed.

“Even if digital platforms are not close enough to common carriers, legislatures might still be able to treat digital platforms like places of public accommodation,” Thomas continues. “The similarities between some digital platforms and common carriers or places of public accommodation may give legislators strong arguments for similarly regulating digital platforms.”

It’s not the first time Thomas has used a tech-related petition as an opportunity to call for social media regulation. In October, Thomas laid out a similar call to pare back the protections offered by Section 230, in a similar motion denying a petition to hear a malware case.

Notably Thomas’ most recent argument cites a law review article by Michigan State professor Adam Candeub, who served in the Commerce Department under Trump. Candeub played a role in drafting an NTIA petition to reshape Section 230 through the regulatory process, which would have positioned the FCC as the de facto regulator of social media platforms.