Earlier this week, a federal appeals court ruled that President Donald Trump couldn’t block his critics on Twitter. More specifically, the court determined that Trump’s Twitter account is a “public forum” where citizens have a right to engage with his comments, the same way they’d be able to attend a town hall. This ruling could shape how all government officials use social media — from the US president to local garbage collectors.

The Knight First Amendment Institute at Columbia University sued Trump in 2017, arguing that Trump had violated the First Amendment rights of seven Twitter users — all of whom had been blocked after tweeting criticism at the @realDonaldTrump account. The Knight Institute argued that Trump was preventing these users from participating in a public discussion since these discussions were taking place in replies to Trump tweets.

A lower court ruled in favor of the Knight Institute last year. The Second Circuit Court of Appeals agreed on Tuesday, saying it was unlawful for “a public official who utilizes a social media account for all manner of official purposes to exclude persons from an otherwise‐open online dialogue because they expressed views with which the official disagrees.”

Trump can say what he wants, but he can’t stop other people from participating

As Cornell Law School professor James Grimmelmann puts it, “Of course Trump can say whatever he wants” on Twitter. And he can choose to boost specific posts by retweeting them. But he can’t make it harder for certain people to participate in the conversation around those tweets, which is exactly what blocking somebody on Twitter does.

Grimmelmann says the facts in this case were “particularly stark” since Trump clearly uses Twitter as an official White House communication tool. But it raises questions for other politicians and governmental agencies. Rep. Alexandria Ocasio-Cortez was recently sued for blocking Republican primary candidate Joseph Saladino, and courts will have to decide whether she’s created the same kind of public forum with her social media presence. “[Trump] made this a very easy case. It’s a harder question if a politician is using it to interact with the public but is not claiming to use it for official business,” he says.

Overall, “what this case pushes toward is a pretty strong separation of official and personal capacities,” says Grimmelmann. If you’re a politician maintaining a mostly campaign-focused or personal account, the ruling might not matter. Otherwise, “it pretty much tells you that your social media presence kind of has to be one-way: you can respond to interact with people, but you’re not going to be able to use anything stronger than muting on inbound content.”

Kendra Albert, an instructor at Harvard Law School’s Cyberlaw Clinic, believes the Second Circuit’s decision is unnecessarily ambiguous. The Trump administration has argued that its account is government speech, or speech that the government is performing on its own behalf, which isn’t regulated by the First Amendment. Albert argues that the original ruling clearly separated the account’s “government speech” content from the interactive forum in the replies. “The lower court decision actually does a really good job of explaining why it matters that people are blocked, even if they can just log out of Twitter and see the president’s tweets otherwise,” Albert said, “and it’s because there’s sort of this discursive space going on underneath the tweet.”

“Does this case mean that they can’t remove comments screaming that recycling is a communist plot?”

The new ruling refers to Trump’s whole account as a public forum, then draws finer lines between tweets that are government speech and independent tweets by other users. “I think it’s still a case that can be cited by plaintiffs in order to show that government officials can’t sort of just be willy-nilly blocking people from their official Facebook or Twitter pages,” Albert says. “But it’s certainly less clear than the district court opinion and it means they have to spend more time explaining why things aren’t government speech.”

Government accounts will need to block some users if they want to keep their digital spaces usable. The ruling doesn’t prevent this, but administrators will have to avoid doing it in a way that’s politically biased, which could lead to some difficult decisions. What if, Grimmelmann says, a municipal waste authority accepts comments on a Facebook page about trash collection? “Does this case now mean that they can’t remove comments screaming at them that recycling is a communist plot?” he asks.

The same difficult decisions could come up with harassment. “It may be difficult to ban or block someone for harassing you kind of generally, unless you have a sustained pattern of harassment,” says Albert. The best solution, they suggest, would be for officials to establish clear moderation rules that could be enforced across the board, the way a town hall could expel people who genuinely disrupt a meeting, even if they’re engaging in political speech.

This doesn’t mean all of Twitter is a public forum

There’s tension between First Amendment protections and social media moderation rules. White supremacist rhetoric is protected under American law, for instance, but it’s banned as hate speech on Facebook. Grimmelmann says that this speech could still be removed as long it’s based clearly on Facebook’s moderation guidelines, not the government’s.

Crucially, this case doesn’t discuss whether Twitter itself is a public forum or determine how Twitter can moderate users. It just rules on the actions that individual government-related accounts can take.

It’s also not the final say on government social media accounts. The Fourth Circuit Court of Appeals ruled in January that county officials couldn’t bar critics from their Facebook pages. But a different court has maintained that Kentucky’s governor can block constituents on Facebook and Twitter. “I think that as different circuits coalesce around a kind of collective test — or at least a way of handling things like Twitter and Facebook and maybe Instagram,” says Albert, “it’ll sort of become more consistent over time.”