## Facts

- Several Twitter users and a free-speech institute alleged that President Donald J. Trump blocked them from interacting in the reply threads associated with tweets from the @realDonaldTrump account because of their criticism.
- Plaintiffs claimed the interactive reply space associated with the account functioned as a public forum and that blocking based on viewpoint violated the First Amendment.
- The district court held the interactive spaces were a public forum and that blocking critics constituted unconstitutional viewpoint discrimination.
- The Second Circuit affirmed, concluding Trump acted under color of law and that excluding users from the reply threads based on viewpoint violated the First Amendment.
- While a petition for certiorari was pending, Joseph R. Biden, Jr. became President and Twitter permanently removed the @realDonaldTrump account from the platform.

## Issues

1. Whether intervening events rendered the dispute nonjusticiable such that the case became moot on Supreme Court review.
2. If moot, whether the proper disposition was to vacate the lower-court judgment and remand with instructions to dismiss under the Munsingwear practice.

## Decision

- The Court granted certiorari, vacated the Second Circuit’s judgment, and remanded with instructions to dismiss the case as moot.
- The Court did not decide the First Amendment merits concerning public forum doctrine, state action, or viewpoint discrimination in social-media reply threads.
- Justice Thomas concurred, emphasizing tensions created when a private platform retains ultimate control over the existence and accessibility of the alleged forum.

## Legal Principles

- Federal courts lack authority to decide cases that become moot due to intervening events eliminating a live controversy.
- When a civil case becomes moot while pending Supreme Court review, the established practice is to vacate the judgment below and remand with directions to dismiss, preventing unreviewed decisions from having ongoing legal effect.
- A public-forum analysis is complicated where a privately owned platform can unilaterally remove an account and thereby terminate the space in which speech and interaction occur.
- Legislative or judicial treatment of dominant platforms may implicate analogies to common carriers or public accommodations, though no rule was adopted.

## Conclusion

The Supreme Court resolved the case solely on mootness grounds, vacating the Second Circuit’s merits ruling and directing dismissal, leaving unresolved the constitutional questions about public officials’ social-media accounts and the status of platform-hosted interactive spaces.


Biden v. Knight First Amend. Inst. at Columbia Univ., 141 S. Ct. 1220 (2021)