For almost three years, Facebook has pulled off an impressive balancing act. It has become one of the most powerful companies in media—the whims of its News Feed can determine the fate of whole news organizations—but it has never quite itself been a member of the press.

Its felicitous run may now have ended. In at least one non-negligible way, Facebook joined journalism’s dirty ranks this week, as the company found itself accused of having a liberal bias.

And perhaps it really does. A series of Gizmodo reports have raised new information about how the company’s “Trending” module works. “Trending” is the list of popular headlines that appears in the top right of Facebook.com; it also appears under the search bar in its ubiquitous mobile app. While many users believed that this module was compiled algorithmically, Gizmodo (and now The Guardian) have revealed that humans, working on contract for the company, guide its creation every step of the way. What’s more, these workers (often Ivy-educated twenty-somethings) “routinely suppressed conservative news,” according to the allegations of one former employee who talked to Gizmodo.

Facebook bills its platform as transparent and apolitical, so this could be disastrous (or at least embarrassing) for it. But as Kashmir Hill writes at Fusion, there isn’t yet definitive evidence that Facebook actually did routinely suppress conservative news. Instead, former employees and leaked corporate documents indicate the workers were told to to amplify news and stories from traditional or name-brand news organizations like CNN, Fox News, and The New York Times. At the same time, they were advised to avoid floating rumors or conspiracy theories from newer, less reliable, and ideologically slanted sites like Newsmax. (The Guardian and Gizmodo reports disagree about whether Breitbart, a far-right and factually unreliable news site, was a “trusted source” or a specifically untrusted one.)

Mark Zuckerberg, the company’s CEO, has now said that in an internal investigation, the company could find no evidence of story suppression. And in some ways, you could see the company’s editorial hand in “Trending” as part of its longtime emphasis on distributing “high-quality content.”

But we might know more later this month. Senator John Thune, a Republican of South Dakota, has formally asked Facebook to answer questions about its neutrality in running the feature. Company representatives have also been asked to meet with staff from the Senate Committee on Commerce, Science, and Transportation.

Senator Thune made those requests in a letter to Facebook—a remarkable document that it’s worth spending some time with. That’s because, before asking specific questions, Thune raises the following concerns:

[W]ith over a billion daily active users on average, Facebook has enormous influence on users’ perceptions of current events, including political perspectives. If Facebook presents its Trending Topics section as the result of a neutral, objective algorithm, but it is in fact subjective and filtered to support or suppress particular viewpoints, Facebook’s assertion that it maintains a ‘platform for people and perspectives from across the political spectrum’ misleads the public.

This is an fascinating implication. Facebook has said it is a platform for perspectives from “across the political spectrum,” but it specifically never has claimed that it will give all those perspectives equal weight. It promises that it will give everyone a place for their ideas, but not that it will be particularly fair about it.

Yet just by talking about misleading the public, Thune is presuming an incredible thesis: that in order for Facebook to make space for all viewpoints, it must be balanced. Which is funny, because Thune has gone on the record a great deal about the role of a government official in regulating media fairness. From the mid-2000s to its eventual repeal in 2011, Thune was one of the lead critics of the Fairness Doctrine, a requirement from the Federal Communications Commission that broadcast stations present “controversial topics” in an honest and balanced way. In fact he often advocated for its repeal (even though it was overturned by the courts in the 1980s).

“Our support for freedom of conscience and freedom of speech means that we must support the rights granted to even those with whom we disagree,” Thune said in June 2007. “Giving power to a few to regulate fairness in the media is a recipe for an Orwellian disaster.”

He elaborated on those views in an article for RealClearPolitics. “I know the hair stands up on the back of my neck when I hear government officials offering to regulate the news media and talk radio to ensure fairness,” he wrote. (The FCC formally repealed the Fairness Doctrine on its own prerogative four years later.)

Thune didn’t just oppose any government regulation of the media—he opposed nearly any government interference in the Internet at all. He has repeatedly opposed the FCC’s efforts to ensure net neutrality, the principle that every web host should have equitable access to the same speed of Internet connection. “The FCC’s decision to adopt controversial regulation of the Internet is yet another example of the heavy hand of government reaching into an industry that isn’t broken and doesn’t need to be fixed,” he said in 2010. And last year, he decried the commission’s announcement that it will strongly enforce net neutrality—or, as his office has put it, “government control of the Internet.”

Of course Thune isn’t advocating for the regulation of Facebook yet. And he can make a big fuss about Facebook’s neutrality without actually legislating anything—in some ways, the company will be damaged more by a partisan fight. But it is an example of how, to paraphrase the senator, those with whom we disagree can make us doubt our own support for the freedom of speech.