Facebook’s fact-checking program is designed to stop false information from spreading. But being able to decide what’s true can also be a political weapon, and for the past few days, it’s been used in a fight over President Donald Trump’s coronavirus response.

The battle centers on a recent Politico article about a South Carolina Trump rally, where Trump urged supporters to “treat coronavirus as a ‘hoax.’” According to Facebook, this is a false statement that merits a prominent warning and potential damage to Politico’s ability to reach Facebook users — but the truth is more complicated.

Judd Legum’s newsletter Popular Information lays out the full contours of the controversy. Essentially, Politico’s Facebook post was flagged by Check Your Fact, a fact-checking group linked to conservative website The Daily Caller. Check Your Fact took issue with the post’s title and its text: “President Trump on Friday night tried to cast the global outbreak of the coronavirus as a liberal conspiracy intended to undermine his first term, lumping it alongside impeachment and the Mueller investigation.”

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Check Your Fact rated Politico’s claims “false information,” explaining that “Trump referred to the alleged ‘politicizing’ of the coronavirus by Democrats as ‘their new hoax.’ He did not refer to the coronavirus itself as a hoax.” Since the site is one of Facebook’s trusted fact-checking partners, Facebook then splashed a warning over posts linking to the article.

As Legum explains, though, Trump’s comments were characteristically ambiguous. He argued that “Democrats are politicizing the coronavirus” to make him look bad. Then, he launched into a comparison with his impeachment:

“One of my people came up to me and said: Mr. President, they tried to beat you on Russia Russia, Russia. That didn’t work out too well, they couldn’t do it. They tried the impeachment hoax, that was on a perfect conversation. They tried anything, they tried it over and over, they’ve been doing it since you got in. It’s all turning, they lost, it’s all turning, think of it. And this is their new hoax.”

Trump surrogates said after the rally that he wasn’t calling coronavirus a hoax. “He was referring to the way he had been treated by the opposite party … in terms of taking every opportunity to bring him down,” said Surgeon General Jerome Adams on SiriusXM’s The Black Eagle with Joe Madison. And you can argue that Trump is limiting his claim to Democrats arguing he’s not prepared for the coronavirus. But the speech simply compares coronavirus to the “impeachment hoax” (which Trump describes as a “perfect conversation” that Democrats twisted into something negative), so it’s also easy to argue that Trump is saying the coronavirus itself is similarly overblown.

In short, Trump is making a weird and unclear statement, followed by conflicting notes on how seriously we should be taking the coronavirus outbreak. And The Daily Caller’s fact-checking wing is using its power — fairly or not — to push an interpretation favored by Trump, who has in fact made reckless and false claims downplaying the threat.

Legum argues that The Daily Caller’s seriously flawed editorial record makes it unfit to judge truth. But even leaving that aside, fact-checking is often politically fraught — The Washington Post has been accused of nitpicking claims by Sen. Bernie Sanders in an ideologically motivated way as well.

Perhaps the most notable thing about this case is that conservatives are usually the ones arguing Facebook has censored them. Now, figures like Donald Trump, Jr. are celebrating the fact that “Facebook [weighed] in” on their side.

So far, nobody involved is changing their mind on the situation. In response to questions from The Verge, a Facebook spokesperson said that “all fact-checkers on Facebook are certified by Poynter’s International Fact-Checking Network and work independently of Facebook. There’s an appeals process in place for publishers to dispute a rating by reaching out directly to any certified fact-checker.” The spokesperson also directed us to a tweet by journalist Mathew Ingram, who defended The Daily Caller’s interpretation.

The Daily Caller’s editor-in-chief Geoffrey Ingersoll told Popular Information that the fact-check was “correct.” Meanwhile, Politico communications manager Brad Dayspring defended his site’s work. “We stand by the reporting and are proud of Politico’s long established reputation for accurate, nonpartisan, and impactful journalism,” he told The Verge.

But whichever side you take, it’s clear that Facebook fact-checking is a powerful tool. Articles that are rated false can have their visibility severely limited, and posting false information can damage the site’s overall rating with Facebook’s algorithm. Fact-checking is a response to a serious misinformation problem on social media, and there are a lot of clear-cut coronavirus hoaxes floating around. But that system also makes Facebook — and more importantly, its partners — an arbiter of truth. Users are left hoping that Facebook’s fact-checking seal of approval is used in good faith.