Facebook's Chief Security Officer has admitted that conversations on the site are monitored by software looking for potentially worrying interactions. If something is spotted, a Facebook employee will read your conversation and decide whether or not to call the police.
So does this go too far in compromising your privacy, or is it a price worth paying?
Tracking criminalsThe details emerged in a report by Reuters, which interviewed Facebook's CSO, Joe Sullivan. It looked at the issue of how websites prevent potential sex offenders using the site to find victims.
Those under the age of 18 are protected to a certain extent because they don't show up in searches, only friends of friends can send them messages and only friends can chat with them. Of course, this does little to protect them against adults assuming another identity, or pretending to be children.
ScreeningIn addition, all conversations are automatically screened. They look for inappropriate language used with someone under 18, and exchanges of personal data. The software was built using actual conversations by offenders which preceded attacks.
You'd have to go a long way to find someone who would object to this sort of screening.
Other crimesHowever, Facebook also monitors conversations for other reasons. Its security pages says that if there ongoing criminal and civil investigations or court cases it will work with the authorities "if we have a good faith belief that the response is required by law."
It will also: "Share information when we have a good faith belief it is necessary to prevent fraud or other illegal activity, to prevent imminent bodily harm, or to protect ourselves and you from people violating our Statement of Rights and Responsibilities. This may include sharing information with other companies, lawyers, courts or other government entities."
ConcernsIt means that if it thinks you are committing a crime of any kind it can contact the authorities and launch an investigation. This starts to cross more lines between privacy and protection. Facebook has been widely used in prosecutions - from a Boston murder investigation, to any number of tax investigations and prosecutions where it is looking for evidence that you are making money and not declaring it.
It raises the issue of what you are opening up to the authorities unwittingly. Could they be interested in activities you thought were a private matter? Could they be misinterpreted? If you are having a jokey conversation with a friend about an 'in-joke' relating to a fictitious crime, could you land yourself in hot water?
What do you think? Is Facebook just doing the right thing, or has it overstepped the mark on privacy? Let us know in the comments.