The social news website and community Reddit has been forced to ban sexually suggestive images of children, after its longstanding policy of not "limiting" what its members did on the site was widely condemned.
Users had been openly posting sexualised images of children on forums including those named "JailbaitVideos" and "PreTeen_girls".
Now the forums have been banned - but some users of the site are angry, claiming it may be the start of a "slippery slope" leading towards greater censorship online.
And even after the ban Reddit has come under further criticism for continuing to host forums dedicated to pictures of dead children.
Reddit, which is based in the United States, allows millions of users to share links, images, video and news stories on an almost endless variety of topics.
The site was bought in 2006 by Conde Nast before being spun off as a subsidiary of the magazine publisher's parent company Advance Publications.
While much of the content shared on the site is the usual blend of tech news, world politics, Internet memes and viral videos familiar to the rest of the web, albeit traditionally with a higher level of depth than some competitors, other areas of its site frequently cross boundaries that even the site's operators find uncomfortable.
But beyond a few basic rules, which include "no spamming, no cheating, no personal info, nothing illegal, and no interfering the site's functions," it's pretty much anything goes.
The result is an anarchic system of sub-groups ('sub-Reddits') on almost any topic - including many that appeared to outside observers - and many users of the site itself - as highly controversial and offensive, at the very least.
Several of the groups were explicitly dedicated to posting sexually suggestive images of underage boys and girls ('jailbait').
Other groups were apparently created to share links to images of dead children, torture and abuse.
Among the groups were those named:
Various media outlets, including CNN, have made attempts to "expose" the site's darker side, but Reddit has always resisted the full implications of the criticism.
Even when Gawker exposed two members apparently trading pornography featuring a 14-year-old girl, the site did not change its general policy even though it did shut down the specific sub-Reddit in question.
Reddit general manager Erik Martin said in response to the CNN report:
"We’re a free speech site and the cost of that is there’s offensive stuff on there."
"Once we start taking down some things we find offensive, then we’re no longer a free speech site and no longer a platform for everyone. We’re exerting editorial control and that’s not what we are."
Its users appeared to agree. The "Jailbait" section exposed by Cooper won the "best of Reddit" poll in 2008 by a margin of 2-to-1.
But now, after users on another online community, Something Awful, gathered together to post a much longer list of the offensive groups, Reddit has been forced to act.
In a blog post titled "A necessary change in policy", the site said:
"Child pornography is a toxic and unique case for Internet communities, and we're protecting reddit's ability to operate by removing this threat. We remain committed to protecting reddit as an open platform."
In the post Reddit emphasised that it had always acted against anyone posting explicit "child pornography", but that a "grey area" had been exposed around sexually suggestive material featuring minors that it could no longer tolerate.
"We have changed our policy because interpreting the vague and debated legal guidelines on a case by case basis has become a massive distraction and risks reddit being pulled in to legal quagmire."
"As of today, we have banned all subreddits that focus on sexualization of children."
Some users of Reddit attempted to defend the right to post the suggestive images.
"Apparently free speech doesn't matter as much to these people as not getting creeped out does."
Others decried the policy as one made by "thought police":
"This crack down is inherently wrong," one user said. "Its not the pictures that are sexual its the perception of the individuals viewing them. Basically what reddit has done is take down legal pictures because of the way people interpret them. Its literally thought policing."
Despite the move, Reddit maintains it is "adamant about not limiting the ability to use the reddit platform even when we do not ourselves agree with or condone a specific use".
Groups still viewable on Reddit as of press time but not viewed by the Huffington Post, according to the blog Extreme Tech, include those dedicated to pictures of dead children and pictures of domestic abuse against women.