1/10/2016 11:40:27 AM (updated 1/10/2016 11:54:28 AM)
There is an Executive Order concerning classified national security information. Hound is right about the classifying authority. Someone some where has to decide information is classified, and that person can conversely decide that certain information is no longer classified. The "declassify after X years" rule is sort of a catchall declassification schedule when the information doesn't warrant special treatment. You may find the acronym "OADR" on some classified documents as well. The acronym stands for "Originating Agency's Determination Required" and it basically means that the person or office deciding classification has to be consulted and give approval before another person or agency declassifies the information.
I think HRC would be opening a huge can of worms if she were to now to backtrack and admit there was information on her server that was classified but is not now. If she were to be the classifying authority for some of the information she could have mounted that defense early on, but would run the risk that part of the classified information on that server belonged to an Agency outside the State Department (e.g., Director of Central Intelligence). It is in a way amusing to watch her squirm.