Elon Musk’s Twitter sparked an international outcry Thursday by suspending a number of journalists at major news organizations who cover him.
But another and possibly related move that Twitter took around the same time, against a fast-growing rival, could open the company up to regulatory scrutiny, some legal experts say.
In addition to suspending journalists who had covered a controversy related to the third-party tracking of Musk’s private jet, the platform also suspended the official Twitter account of rival Mastodon after it tweeted about the ElonJet account.
Twitter users began tweeting links to their Mastodon profiles, and some half-jokingly told followers where they could be found on the alternative platform in case they too were banned from Twitter without warning.
Soon, however, Twitter began throwing up roadblocks—marking links to Mastodon as “unsafe” and potentially malicious, blocking tweets containing those links, and preventing users from adding Mastodon links to their profiles.
Now legal experts are pondering whether there could be anti-competitive or other regulatory implications as a result of Twitter’s blocking of Mastodon links.
“You can see all kinds of problems, both from a competition and a consumer protection standpoint,” said Bill Baer, who has served as the former top antitrust official at the Justice Department and at the Federal Trade Commission across two separate U.S. administrations.
Those questions, which bring to light on Twitter some of the antitrust investigation that has been leveled at major tech giants Meta and Google, come just as Twitter faces growing questions about its ability to comply with a US consent decree — along with concerns about hate speech on the platform and the possible precedent set by its suspension of journalists reporting on Musk.
Twitter, which has cut much of its PR team, did not respond to a request for comment.
As news of the journalist suspensions spread, many Twitter users announced they were migrating or expanding to Mastodon. But the sudden restrictions Twitter placed on link sharing appeared to thwart some attempts to direct users to the alternative platform.
“Twitter is now attempting to prevent users from navigating to the official social media accounts of elected officials on other platforms,” said Virginia Democratic Representative Don Beyer, sharing a screenshot of a Twitter system message warning that Beyer’s link to his Mastodon profile was “potentially spam or unsafe.”
Other users, such as New York Times editor Patrick LaForge, observed that attempts to add Mastodon links to Twitter profiles produced error messages from Twitter warning that the links were “considered malware.”
CNN confirmed some of the reports with its own testing, finding that Twitter was blocking attempts to tweet links directing users to a Mastodon profile. Sharing Mastodon user handles as plain text, and using link shortening services that obfuscated the destination address, allowed users to get around the restrictions. But the link blocking continued till Friday afternoon.
Musk has falsely claimed that the suspended journalists were sharing real-time information about his physical location, in violation of Twitter’s guidelines. After one of the suspended reporters challenged Musk’s claim at a Twitter Spaces event that Musk had stopped by Thursday night, the new Twitter owner abruptly left the conversation.
Eugen Rochko, founder and CEO of Mastodon, has not publicly addressed Twitter’s link blocking, but has reinforced a public report about it. CNN has reached out to Rochko for comment.
Although there are some differences in how the two platforms work, Mastodon’s user experience replicates much of the basic Twitter functionality. Twitter is much bigger, with about 238 million users to Mastodon’s one million, but the latter has grown rapidly since Musk bought Twitter. In the first week and a half after Musk closed his Twitter deal, Mastodon gained hundreds of thousands of users, and the migration has only continued ever since.
Twitter’s move to block links to a nascent rival could be the kind of activity to pique the interest of the Federal Trade Commission, whose head, Lina Khan, has vowed to crack down on new ways tech platforms might try to harm competition.
If regulators could prove that Twitter intentionally used the link block to preserve some form of market dominance and to keep a potential rival at bay, then they might have a case, legal experts say.
In general, companies are not obliged to do business with each other and are free to choose their business partners. But a dominant firm said to have “market power” could potentially violate antitrust laws if it refuses to deal with other parties.
This notion of a “duty to act” is probably the most relevant to this situation, according to Charlotte Slaiman, director of competition policy at the consumer advocacy group Public Knowledge and a former FTC antitrust official.
“If Twitter has market power, it may have some obligations to deal with competitors,” Slaiman said. “Deal to deal is an area of antitrust law that I think is very important in the technology sector, but has been aggressively curtailed” in recent decades.
Under Khan, a vocal tech skeptic, the FTC has shown an expanded interest in duty-to-deal cases through recent policy statements, Slaiman added. And under the Trump administration, the FTC alleged that Facebook had acted anticompetitively by effectively blocking access to Vine, a Twitter-owned video platform, as part of a broader lawsuit seeking to break up the social media giant. (The FTC complaint was later thrown out by a federal judge, but refiled with slightly different arguments on Khan’s watch.)
A case involving a duty to act would likely have to argue that Twitter had somehow harmed itself by restricting Mastodon link sharing – perhaps by making itself less likely to receive inbound traffic from Mastodon, or by make themselves less attractive to advertisers as an open platform. At the same time, it would probably also need to show that Twitter’s actions hurt Mastodon even worse, by taking something critical away from it (in this case, potentially an influx of new users).
Before that, however, a judge must first agree that Twitter has “market power” or dominance in a specific market that regulators are expected to describe and explain in any lawsuit. That definition can take a number of different forms, but it must be reviewed with the judge before prosecutors even have a chance to argue that Twitter’s conduct was anticompetitive.
It could be a tough case, said Baer and Slaiman.
Baer added that Twitter’s link blocking doesn’t just raise potential competition concerns. It also raises questions about Twitter’s stated reasons for blocking the links, and whether those public reasons stand up to scrutiny by consumer protection authorities.
While Beyer was tweeting, the link he shared to his own Mastodon profile was not malicious. And until Thursday, there appeared to be no basis for Twitter to claim that Mastodon links were unsafe.
If Twitter misled the public with its statements about Mastodon links, saying they were spam or malicious when the company knew they were harmless, for example, the FTC could potentially try to argue that Twitter acted unfairly or deceptively, according to Baer.
The FTC has historically had wide latitude to prosecute alleged unfair and deceptive business practices. And it is crucial that these cases do not require demonstrating market power.
With the FTC already closely monitoring Twitter’s behavior under Musk, the Mastodon issue could lead to additional scrutiny that the company cannot afford.