ZUCKERBERG: 'No evidence' to support Trending News controversy

Mark Zuckerberg says that Facebook has found "no evidence" to support a report from Gizmodo that alleges that the editors running the website's Trending News panel buried news from outlets with a politically conservative slant, and promoted non-trending stories that were more liberal in nature.

"We have rigorous guidelines that do not permit the prioritization of one viewpoint over another or the suppression of political perspectives," Zuckerberg wrote in a Facebook post on Thursday.

The controversy arose after Gizmodo's report quoted several former news "curators" who said that the team routinely omitted articles from conservative news sources and could make objective decisions to "inject" stories that weren't actually trending.

Earlier today, Facebook posted the guidelines it gives its news curators on how to pick stories that appear in the Trending News panel. Those guidelines say that curators are supposed to blacklist news posts only if they're false or if they duplicate another topic already covered. They also say that curators may inject stories, but only if they're shown to be trending by an alternate tool (the "Trending Demo" tool) that the curators don't normally use. They are not supposed to inject topics based on their own editorial judgment.

Zuck's full response is here:

This is the part of Facebook everybody's in an uproar about - not the main news feed, but the little "Trending" box to the side: