How the US surveillance machine grew too big for even anyone at NSA to understand

Newly declassified documents tell a story of a U.S. surveillance apparatus so unwieldy and complex that nobody fully comprehended it, even as the government pointed it at the American people in the name of protecting them.

The National Security Agency set it in motion in 2006 and the vast network of supercomputers, switches and wiretaps began gathering Americans' phone and Internet records by the millions, looking for signs of terrorism.

But every day, NSA analysts snooped on more American phone records than they allowed to. Some officials searched databases of phone records without even realizing it.

Documents from the Foreign Intelligence Surveillance Court show that even senior lawyers and officials weren't sure how the system worked and didn't understand what they were told.