Facebook uncovered no evidence that it suppressed news about conservative issues in its "trending topics" feature, the social media firm wrote Monday in a letter to U.S. Senate Commerce Committee Chairman John Thune (R-S.D.).
"Our data analysis indicated that conservative and liberal topics are approved as trending topics at virtually identical rates," Colin Stretch, Facebook's general counsel, said in a prepared statement. "We were also unable to substantiate any of the specific allegations of politically-motivated suppression of particular subjects or sources."
As part of Facebook's internal investigation, Stretch said the company spoke with current reviewers who oversee "trending topics" as well as with their supervisors, former reviewers and contractors, and reassessed its guidelines.
Stretch added that the investigation could not rule out isolated incidents of "improper actions or unintentional bias," so the company will change the way it handles trending topics to "minimize risks where human judgment is involved."
The world's largest social network came under fire earlier this month after tech news site Gizmodo reported that former contractors who ran the "trending topics" feature downplayed news from conservative outlets and about conservative topics.
Chairman Thune subsequently sent Facebook Chief Executive Mark Zuckerberg a letter, stating that "Facebook must answer these serious allegations and hold those responsible to account if there has been political bias in the dissemination of trending news."
Zuckerberg met with conservative leaders last week to assure them of Facebook's neutrality.