Last night, Twitter banned one of its most infamous users: the Breitbart editor and conservative pundit Milo Yiannopoulos. In a statement sent to Recode, Twitter said that while "people should be able to express diverse opinions and beliefs on Twitter ... our rules prohibit inciting or engaging in the targeted abuse or harassment of others." A screenshot posted to Breitbart said much the same thing, adding that the account was being banned permanently because he had been given similar warnings in the past.

The ban came after a high-profile harassment incident involving Ghostbusters star Leslie Jones, who was subjected to huge volumes of racist and misogynist abuse shortly after Yiannopoulos published a review that called Jones "spectacularly unappealing." Yiannopoulos joined in with his own mockery on Breitbart and Twitter, posting a series of fake screenshots that supposedly showed Jones spouting anti-semitic and homophobic slurs. Finally, Twitter CEO Jack Dorsey directly reached out to Jones — and a day later, Yiannopoulos’ handle @Nero had been permanently suspended.

It’s unclear whether Twitter objected to a single tweet or a general problem

This is a fairly straightforward listing of the facts. But although Yiannopoulos has arguably done plenty to deserve a ban, we don’t know why Twitter acted now. Yiannopoulos' tweets were deleted when the account was pulled, and Twitter didn't provide examples of the targeted abuse or harassment he was banned over. His Ghostbusters review, while negative, didn’t single out Jones, and he wasn’t directly responsible for the more egregious messages she got. So was he suspended over a specific tweet, like the screenshots? Did Twitter decide his gloating was encouraging her harassers? After years of complaints over generally trollish behavior, did Twitter just decide enough was enough?

Consequently, we can’t tell if Yiannopoulos finally crossed a clear line, or if Twitter is only paying attention because the abuse hit a celebrity like Leslie Jones. We can’t examine or dismiss Yiannopoulos’ long-standing claim that he’s been targeted for his conservative views. We can’t know what kind of harassment reports Twitter will take seriously when people besides Jones submit them.

More importantly, we can’t figure out what kind of environment Twitter actually wants to create. Compared to other big social networks, Twitter offers people a wide reach but little control over their social interactions — even its blocking system, the main tool for combating harassment, can be circumvented by creating a throwaway account or just logging out. Because rank-and-file users can do so little by themselves, Twitter’s top-level decisions about its community standards have a huge impact on their experience, far more than banning a Facebook page or a Snapchat user.

Twitter users have relatively little control over their social interactions

And there are few good points of comparison that we can look to for help. Popular Twitter users can direct thousands of reactions toward someone just by mentioning their Twitter handle, so people like Yiannopoulos can consciously cultivate a following of hateful trolls, post their target’s name, and sit back with technically clean hands, knowing that their fans will handle the harassment for them. Unlike an explicit threat, this isn’t illegal, and it might even sound innocuous to anyone who’s not familiar with Twitter. But it’s one of the worst flaws of the platform, and it’s much harder to consistently identify and combat.

Beyond simply building better tools for blocking and filtering — one of the best ways to fight trolls — solving a harassment case like Jones’ requires nuance. It means examining context and figuring out whether someone knowingly meant to cause harm to another person, so well-meaning users don’t end up getting blamed for some bad followers’ actions. These are the kind of judgment calls actual courtroom juries have trouble making, let alone a bunch of overworked Twitter moderators. It’s not even clear that Twitter has a good structure in place to deal with these problems, even if it's trying to create one. The harassment Leslie Jones faced happens to Twitter users every day, but it took a direct conversation with the CEO to address it.

Obviously, a Twitter ban is orders of magnitude less serious than a criminal conviction, whatever the pro-Yiannopoulos #FreeMilo hashtag implies. But it’s not nothing. Just as we shouldn’t tell harassment victims to "just log off" the internet, we shouldn’t pretend that being kicked off a platform with millions of users doesn’t cut you off from some part of modern public life, and Twitter should be careful with the power it’s got.

Everyday users can’t hold Twitter to a clear anti-harassment standard

The general opacity of Twitter’s anti-harassment system helps no one. It lets genuinely terrible people argue they’re victims, creates uncertainty for anyone whose unpopular opinions don’t cross over into harassment, and gives everyday users no way to figure out what they can expect from the platform. If someone thinks they’re being harassed, they can’t hold Twitter to a strong, clear, consistent standard for addressing it — they can’t even point to something like Yiannopoulos’ ban as a precedent, because they don’t know what he did.

Maybe this is intentional. The more specific Twitter’s policies, the more flack it will get when someone’s nasty tweet slips through the cracks, which is almost certain to happen on such a large platform. But in the long term, if we’re going to fight abuse on Twitter, we need to at least know what Twitter thinks that means.