Twitter has a new policy that any tweets with links to Substack cannot be retweeted, liked, or commented on.
The reason is pretty obvious: Substack is a competitor to Twitter for attention and the take-o-sphere. In particular, Substack just announced a Notes feature, which is transparently a twitter clone.
This seems like anticompetitive conduct, which would be illegal under Section 2 of the Sherman Antitrust Act, so long as Twitter is a monopolist.
If Twitter is a monopoly, the big legal question is whether a company is “attempting to exclude rivals on some basis other than efficiency” Aspen Skiing Co. v. Aspen Highlands Skiing Corp., 472 U.S. 585, 605 (1985). So if Twitter is (1) worsening its own product to harm Substack, and (2) Twitter has monopoly power, this is an antitrust violation.
(Legal Note, you might also have to show that the ban hurts Substack enough for the ban on retweets to be a semi-reasonable strategy by Twitter . The ban has to plausibly hurt Substack more than Twitter. There has to be enough evidence for a reasonable jury to find the conduct would “likely result in sustained supracompetitive pricing.” Brooke Grp. Ltd. v. Brown & Williamson Tobacco Corp., 509 U.S. 209, 226 (1993). That rule usually comes up in predatory pricing, where over-enforcement of antitrust law is a big problem. Here, I think Twitter would have a hard case. Restricting traffic clearly hurts Substack more than twitter, given the network effects at work).
Banning retweets of Substack links pretty clearly makes twitter a worse product. Many people use twitter to promote their Substacks, discussion on twitter is often about Substacks, etc. Allowing retweets improves ~the discourse~. But you can see how banning retweets hurts Substack more than it hurts Twitter: Twitter is a lot bigger and there are network effects here, so open flow between Substack and Twitter improves Substack a lot more than it improves Twitter, so cutting off Substack keeps Substack from growing.
Twitter did a similar ban on links to Mastodon a while ago but gave that up after a while. In the Substack case I think the antitrust claim is stronger because linking to Mastodon doesn’t obviously make twitter better, but linking to Substack does – links to Substacks form a focal point for a discussion on Twitter, which is a lot of what Twitter does.
Twitter somehow needs to argue that links to Substack somehow make Twitter worse. Perhaps they can argue that when people follow the links, they’re on other websites and the Twitter discourse isn’t as fun.
However, that argument is going to be hard to make, because Twitter doesn’t similarly disfavor links to other news, opinion, and blogging sites like WordPress. Choosing to allow links to most blogs/opinions and only punish links to blogs that happen to be hosted by a Twitter competitor strongly suggests anticompetitive purpose, and also suggests that the ban makes Twitter worse. Twitter maintains features to have external links and allows external links to news, because that feature improves Twitter. It follows that limiting links to Substack probably worsens it.
There’s the further question of whether twitter has monopoly power. It’s not clear how you would define the market, but they clearly have power over Substack. Substack has data on where people came to Substack from. I don’t have that data, personally, but anecdotally it seems to be that most non-subscriber traffic on Substack comes from Twitter:
European Case
I think the DMA has an especially strong case against Twitter. EU Digital markets act says that gatekeeper platforms cannot “prevent consumers from linking up to businesses outside their platforms.” Here, twiteter isn’t explicitly banning links to outside websites, but banning likes and retweets will surely prevent a lot of people from linking to Substack who otherwise would. So it’s a murky case.
It looks like this DMA rule is why they’re limiting links to Substack rather than banning them entirely.
Indefensible Expectations 