The US Senate Commerce Committee today opened an inquiry into Facebook employees' alleged manipulation of the site's news story selection. The committee has legislative oversight of numerous areas of American commerce, including communications and consumer-protection issues. Its chairman, Sen. John Thune (R-SD), signed a letter to Facebook CEO Mark Zuckerberg containing questions about the nature of the company's Trending Topics section following allegations, reported first by Gizmodo yesterday, that contract workers censored stories from conservative outlets.

"Facebook must answer these serious allegations and hold those responsible to account if there has been political bias in the dissemination of trending news," Thune said in a statement. "Any attempt by a neutral and inclusive social media platform to censor or manipulate political discussion is an abuse of trust and inconsistent with the values of an open Internet."

The Senate can't actually make Facebook do anything

To be clear, Facebook can do whatever it likes with any aspect of its social network, including control what it shows to users, as it did in a controversial emotion-manipulation study in 2011. So the Senate committee's letter here is, at best, strategic posturing. You can also see it at as petty grandstanding. It's designed to put pressure on Facebook and show that people in positions of political power are upset with the matter, even if there's nothing the body can do to legislate the company's editorial neutrality

In fact, at least one (high-profile) Senate Democrat is annoyed that Thune and the Senate Commerce Committee feel the need to weigh in at all. "The Republican Senate refuses to hold hearings on Judge Garland, refuses to fund the President's request for Zika aid, and takes the most days off of any Senate since 1956, but thinks Facebook hearings are a matter of urgent national interest," said Sen. Harry Reid (D-NV) in a statement provided to The New York Times by his deputy chief of staff. "The taxpayers who pay Republican senators' salaries probably want their money back."

For what it's worth, the letter asks Facebook to give more information about its editorial guidelines, the structure of the news team, whether any manipulation has taken place, and whether Facebook is investigating the claims at hand. The committee also wants more information about a so-called "injection tool," which curators allegedly used to pin stories in the Trending Topics list that were not in fact popular enough to have been flagged by the system's algorithms.

Facebook says it has "found no evidence" of manipulation

The company has pushed back against Gizmodo's report, saying it does not "permit the suppression of political perspectives" and has never banned a news outlet from appearing in the Trending Topics bar. Facebook search VP Tom Stocky, whose team is responsible for Trending Topics, went further this morning in a Facebook post saying they "have found no evidence that the anonymous allegations are true." Stocky did admit that curators "are instructed to disregard junk or duplicate topics, hoaxes, or subjects with insufficient sources."

That leaves open the possibility that Facebook's news team members are actively choosing which outlets to trust and which to ignore. It's also tacit acknowledgement that its algorithms cannot curate the news without human input, which leaves story selection vulnerable to bias and potential censorship. So the question now is less about whether Facebook can do this type of manipulation and more about whether there's any hard evidence that it does. If there's anything Facebook is good at, it's collecting data, so we may know soon enough.

A Facebook spokesperson, in a new statement given to The Verge this afternoon, says the company has "seen allegations that people did not honor the intent" of its editorial guidelines, and it is "continuing to investigate whether any violations took place." The company also says it plan to address Sen. Thune's questions and provide the committee with more information about how the Trending list functions.

Update at 2:34PM ET on Tuesday, May 10th: Added comment from Sen. Harry Reid.

Update at 4:10PM ET on Tuesday, May 10th: Added comment from Facebook.