Elon Musk’s Twitter sparked an international outcry on Thursday as a number of journalists from major news organizations who covered him were suspended.
But another and possibly related move Twitter took against a fast-growing competitor around the same time could subject the company to regulatory scrutiny, some legal experts say.
In addition to suspending journalists covering a controversy related to third-party pursuit of Musk’s private jet, the platform also suspended rival Mastodon’s official Twitter account after it tweeted about the ElonJet account.
Twitter users began tweeting links to their Mastodon profiles, with some half-jokingly telling followers where to find them on the alternative platform if they too were banned from Twitter without warning.
However, Twitter soon began putting up roadblocks – flagging 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 considering whether Twitter’s blocking of mastodon links could have anti-competitive or other regulatory implications.
“You could see all sorts of problems, both from a competition standpoint and from a consumer protection standpoint,” said Bill Baer, who served as a former chief antitrust officer at the Justice Department and the Federal Trade Commission in two different U.S. administrations.
These questions, which concern Twitter as part of the antitrust scrutiny aimed at larger tech giants Meta and Google, come just as Twitter faces mounting questions about its ability to comply with a US government consent order — along with concerns about Hate speech on the platform and the potential precedent set by the suspension of journalists covering Musk.
Twitter, which has shed much of its PR team, did not respond to a request for comment.
As news of the journalists’ suspension spread, many Twitter users announced that they were migrating or expanding to Mastodon. But the sudden restrictions Twitter imposed on link sharing seemed to thwart some attempts to direct users to the alternative platform.
“Twitter is now attempting to prevent its users from navigating to elected officials’ official social media accounts on other platforms,” said Virginia Democratic Assemblyman Don Beyer, sharing a screenshot of a Twitter system message warning, that Beyer’s link to his Mastodon profile was “potentially spammy or insecure.”
Other users, such as New York Times editor Patrick LaForge, observed that attempts to add Mastodon links to Twitter profiles generated error messages from Twitter warning that the links were “considered malware.”
CNN corroborated some of the reports with its own testing, noting that Twitter blocked attempts to tweet links directing users to a Mastodon profile. By exposing Mastodon user handles as plain text and using link shortening services that obfuscated the target URL, users were able to bypass the restrictions. But the deadlock lasted until Friday afternoon.
Musk has falsely claimed that the suspended journalists shared real-time information about his physical location, violating Twitter policies. After one of the suspended reporters challenged Musk’s claim in a Twitter Spaces event that Musk had spontaneously stopped by Thursday night, the new Twitter owner abruptly left the conversation.
Eugen Rochko, the founder and CEO of Mastodon, has not publicly addressed Twitter’s link blocking, but has expanded on a public account of it. CNN reached out to Rochko for comment.
While there are some differences in how the two platforms work, Mastodon’s user experience replicates much of the basic Twitter functionality. Twitter is much larger, having around 238 million users to Mastodons’ one million, but the latter has grown rapidly since Musk took over Twitter. In the first week and a half after Musk closed his Twitter deal, Mastodon added hundreds of thousands of users, and the migration has continued ever since.
Twitter’s move to block links to an up-and-coming rival could be the kind of activity to pique the interest of the Federal Trade Commission, whose chair, Lina Khan, has vowed to crack down on new ways tech platforms might try to to affect competition.
If regulators could prove Twitter intentionally used link blocking to maintain some form of market dominance and keep a potential competitor at bay, they could have a case, legal experts say.
In principle, companies are not obliged to do business with one another and are free to choose their business partners. But a dominant company that is said to have “market power” may violate antitrust laws if it refuses to do business with other parties.
According to Charlotte Slaiman, director of competition policy at consumer advocacy group Public Knowledge and former FTC antitrust official, this notion of “duty to act” is probably the most relevant to this situation.
“If Twitter has market power, it may have some responsibilities to engage with competitors,” Slaiman said. “Duties to Deal is an area of antitrust law that I believe is very important in the technology sector, but has been aggressively narrowed down over the last several decades.”
Under Khan, a vocal technology skeptic, the FTC has shown a growing interest in duty-to-deal cases through recent policy statements, Slaiman added. And during the Trump administration, the FTC alleged that Facebook acted anticompetitively by effectively blocking access to Vine, a Twitter-owned video sharing platform, as part of a broader lawsuit aimed at crushing the social media giant have. (The FTC complaint was later thrown out by a federal judge, but refiled under Khan’s supervision with slightly different arguments.)
A duty-to-trade case would likely have to argue that Twitter somehow harmed itself by restricting mastodon link sharing—perhaps by making it less likely to accept inbound traffic from mastodon preserved, or by making it less attractive as an open platform for advertisers. At the same time, it would probably also need to show that Twitter’s actions are hurting Mastodon even worse by taking away something crucial from him (in this case, possibly an influx of new users).
Before doing so, however, a judge would first have to agree that Twitter possesses “market power” or dominance in a particular market, which regulators would have to describe and explain in any court proceeding. That definition could take a variety of forms, but it would have to agree with the judge before prosecutors would even have a chance to argue that Twitter’s conduct was anticompetitive.
It could be a difficult case, Baer and Slaiman said.
Baer added that Twitter’s link blocking doesn’t just raise potential competition concerns. It also raises questions about Twitter’s reasons for blocking the links and whether those public justifications stand up to scrutiny by consumer protection officials.
As Beyer tweeted, the link he shared to his own Mastodon profile was not malicious. And before Thursday, there seemed to be no reason for Twitter to claim Mastodon links were unsafe.
If Twitter misled the public with its statements about Mastodon links, such as saying they were spam or malicious when the company knew they were harmless, the FTC could potentially try to argue that Twitter was unfair or acted in a misleading manner, Baer said.
The FTC has historically enjoyed wide latitude to prosecute suspected unfair and deceptive business practices. And crucially, these cases do not require a demonstration of market power.
With the FTC already closely monitoring Twitter’s behavior under Musk, the mastodon issue could prompt another scrutiny the company can hardly afford.