Facebook has started to roll out its “fake news” fact-checking feature, which relies on partisan fact-checkers such as Snopes.

According to The Daily Mail, “Users have reported seeing a pop-up window when they attempted to share articles that were deemed inaccurate by third-party fact-checkers.”

“Facebook itself will not decide what is real and what is considered fake. Instead, it is enlisting The Poynter Institute, a Florida journalism school, to sift through content,” they continued. “The Poynter Institute is the host of the International Fact Checking Network which bills itself as a ‘global alliance of fact checkers’. Its members include ABC News, Politico, The Associated Press, Snopes.com and The Washington Post.”

The Daily Mail provides screenshots and a video of Facebook alerting a user when they attempt to post an article on “The Irish Slave Trade” by Newport Buzz.

“Before you share this content, you might want to know that the fact-checking sites, Associated Press and Snopes.com disputed its accuracy,” alerts Facebook, before giving the user the option to find out more about “disputed content,” cancel, or “post anyway.”

When users click to find out more about “disputed content,” Facebook gives the option to visit the Associated Press and Snopes, along with a caption claiming “sometimes people share fake news without knowing it.”

The term “fake news” has often been used to describe independent or alternative news sources, particularly those with a conservative or libertarian view-point, such as Breitbart News.

In November, a professor at Merrimack College, Massachusetts, included Breitbart News in her “fake news” list, which went viral online. Despite this, several news outlets have been exposed by Breitbart News for publishing their own “fake news,” including the Independent, the Daily Beast, CNN (numerous times), the Atlantic, The New York Times, and The Washington Post.

Despite Facebook’s use of Snopes as an allegedly “neutral” fact-checking service, many of Snopes’ fact-checkers were discovered to be openly left-wing and self-described “progressives.”

Snopes fact-checker Arturo R. Garcia openly labels himself as a “progressive,” attempted to compare Trump supporters to racists on Twitter, misattributed a quote about him to Breitbart News, and acts as the editor of “Racialicious” – “A blog about the intersection of race and culture”.

Fellow Snopes fact-checker Bethania Palmer attempted to link Trump to the KKK, defended a racist professor, wrote numerous left-wing articles for Raw Story — including two attempting to associate former Breitbart News executive chairman Stephen K. Bannon to domestic violence and white supremacy — and acts as a contributor for the “progressive” non-profit Truthout.

David Emery, another fact-checker and staff writer at Snopes, openly asked on Twitter whether there were “any un-angry Trump supporters.”

Despite their clear political biases, all three were tasked with fact-checking political candidates over the 2016 presidential election under the guise of a neutral service.

In February, Apple CEO Tim Cook, who supported Democratic candidate Hillary Clinton during the 2016 U.S. presidential election, called on technology companies to filter out “fake news.”

Facebook CEO Mark Zuckerberg also penned a plan to tackle “fake news” last month, highlighting his intention to roll out the fact-checking feature.

Charlie Nash is a reporter for Breitbart Tech. You can follow him on Twitter @MrNashington or like his page at Facebook.