Edward Snowden showed the world what can happen if information is not adequately protected. As an insider to the NSA (National Security Agency) he had access to very sensitive information, and while he was in the organisation that access was necessary. No doubt there would have been pretty solid authentication and access controls in place, but if your trust is misplaced they are no security at all!
Politics aside, both DLP (Data Loss Prevention) and IRM (Information Rights Management) solutions could have prevented such a catastrophic loss. Data Loss Prevention could have prevented him from copying information into USB memory sticks or CDs/DVDs, or whatever was his media of choice, as well as blocking any attempts to transfer files electronically beyond the NSA's network. Information Rights Management could have protected all the documents no matter where they were or needed to be, controlling what Edward could do with them, like open or print them or copy information from them. Once Ed was rumbled all the document rights could have been revoked leaving Ed with nothing but encrypted data with no keys to unlock them.