In 2013, Edward Snowden, working under contract to the US National Security Agency for the consultancy Booz Allen Hamilton, copied and leaked thousands of classified documents that revealed the inner workings of dozens of previously unknown surveillance programs. One of these was PRISM, launched in 2007, which let NSA use direct access to the systems of numerous giant US technology companies to carry out targeted surveillance of the companies' non-US users and Americans with foreign contacts by…