The controversy - which has drawn critical comment from British Prime Minister David Cameron - illustrates the difficulty of setting a universal standard across the social network used by 1 billion people. Facing sharp criticism, Facebook Inc. issued a statement clarifying that violent videos were only allowed if they were presented as news or held up as atrocities to be condemned.
"If they were being celebrated, or the actions in them encouraged, our approach would be different," the company said in a statement. "However, since some people object to graphic video of this nature, we are working to give people additional control over the content they see. This may include warning them in advance that the image they are about to see contains graphic content."
Facebook banned beheading videos in May but recently lifted the prohibition - a development flagged by the BBC on Monday. A few groups have since condemned the social network for potentially exposing users to the violent content.
Cameron, whose right-leaning government has unveiled several initiatives to censor objectionable content online, said Tuesday allowing the beheading videos back on Facebook was "irresponsible."
Facebook's administrators face constant pressure from interest groups trying to impose their own forms of censorship or fighting to lift restrictions they see as oppressive. Women's rights groups want the company to crack down on misogynistic content; others have ridiculed Facebook's ban on the depiction of female breasts. Some believers have urged the site ban what they see as blasphemous content, while others decry what they claim is Facebook's censorship of pages critical of one religion or the other.
Violent news content poses particularly thorny questions for a website that allows children as young as 13 to join. Should photos of heroic rescuers working during the Boston marathon bombings be banned because some people object to the sight of gore? While images of torture and abuse helped fuel the rage of the Arab pro-democracy demonstrators, should they have been banned for being too bloody?
One free speech group said the fact that content is hard to watch didn't mean it should be hidden.
"Films about beheadings may be deeply upsetting and offensive, but they do expose the reality of violent acts that are taking place in the world today," said Sean Gallagher of the London-based Index on Censorship. "When trying to draw a line about what should or shouldn't be allowed, it's important to look at context, not just content."