Senator: "Facebook must answer these serious allegations."
A US Senate committee on Tuesday demanded that Facebook Chairman Mark Zuckerberg respond to a Monday report in Gizmodo that the social networking site's workers "routinely suppressed news stories of interest to conservative readers from the social network's influential 'trending' news section."

South Dakota Republican Sen. John Thune, chairman of the Senate Committee on Commerce, Science, and Transportation, labeled the allegations in the anonymously sourced Gizmodo piece "serious."

"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 Gizmodo story reported allegations from unnamed Facebook "news curators" alleging that they were instructed to routinely suppress "trending" stories with conservative viewpoints and instead would "inject" other news stories, even if they were not trending. The company claims that it lists "topics that have recently become popular on Facebook."

Facebook denied the allegations.

"We take these reports extremely seriously, and have found no evidence that the anonymous allegations are true," said Tom Stocky, who is in charge of Facebook's trending topics.

Stocky said the decision for which stories trend was indeed based on humans and an algorithm.

"Trending Topics is designed to showcase the current conversation happening on Facebook. Popular topics are first surfaced by an algorithm, then audited by review team members to confirm that the topics are in fact trending news in the real world and not, for example, similar-sounding topics or misnomers."

Thune demands answers by May 24 to these questions:

1 Please describe Facebook’s organizational structure for the Trending Topics feature, and the steps for determining included topics. Who is ultimately responsible for approving its content?

2 Have Facebook news curators in fact manipulated the content of the Trending Topics section, either by targeting news stories related to conservative views for exclusion or by injecting non-trending content?

3 What steps is Facebook taking to investigate claims of politically motivated manipulation of news stories in the Trending Topics section? If such claims are substantiated, what steps will Facebook take to hold the responsible individuals accountable?

4 In a statement responding to the allegations, Facebook has claimed to have “rigorous guidelines in place for the review team” to prevent “the suppression of political perspectives” or the “prioritization of one viewpoint over another or one news outlet over another.”
a. When did Facebook first introduce these guidelines?
b. Please provide a copy of these guidelines, as well as any changes or amendments since January 2014.
c. Does Facebook provide training for its employees related to these guidelines? If so, describe what the training consists of, as well as its frequency.
d. How does Facebook determine compliance with these guidelines? Does it conduct audits? If so, how often? What steps are taken when a violation occurs?

5 Does Facebook maintain a record of curators’ decisions to inject a story into the Trending Topics section or target a story for removal? If such a record is not maintained, can such decisions be reconstructed or determined based on an analysis of the Trending Topics product?
a. If so, how many stories have curators excluded that represented conservative viewpoints or topics of interest to conservatives? How many stories did curators inject that were not, in fact, trending?
b. Please provide a list of all news stories removed from or injected into the Trending Topics section since January 2014.

Facebook, in an e-mail to Ars, said it has received Thune's letter.

"We have seen allegations that people did not honor the intent of those guidelines," the company wrote. "Although the allegations are anonymous, we take them seriously. We are continuing to investigate whether any violations took place."

"As we investigate, we will also keep reviewing our operational practices around Trending Topics — and if we find they are inadequate, we will take immediate steps to fix them," Facebook said. "We have received Sen. Thune's request for more information about how Trending Topics works, and look forward to addressing his questions."