This is very interesting, particularly because this capability exists without people knowing the little clues they leave can be put together in this way. The E

This is very interesting, particularly because this capability exists without people knowing the little clues they leave can be put together in this way. The EU data protection act contains the concept of sensitive personal data thanks to the abuse of people by the Nazis. It includes ethnic origin, religion, medical information and sexuality. The idea is that once you can put together a list of people meeting a particular criteria it's very easy to round them up. While I don't think Facebook or the US are in danger of that kind of excess, neither was Holland before the second world war. Yet one of the reasons for the high death toll of Dutch Jews was the good state of the records: http://en.wikipedia.org/wiki/History_of_the_Netherlands_(1939%E2%80%931945)#High_Jewish_death_toll http://en.wikipedia.org/wiki/History_of_the_Netherlands_(193... I think it might be a good idea for Facebook and others to consider not just the data they have but also the inferences that can be drawn on it, and reflect whether that leaves them with certain responsibilities like easy opt out or not storing certain things.