Security Classification Policy and Procedure: E.O. 12958, as Amended [Updated January 7, 2005] [open pdf - 38KB]
"After two years of preparation, E.O. 12958, prescribing security classification policy and procedure, was signed by President William Clinton in mid-April 1995. The order was prompted by changing security conditions in the aftermath of the end of the cold war and a desire for more economical and effective management of classified information. The directive was modified in late March 2003 by E.O. 13292, issued by President George W. Bush. Largely prescribed in a series of successive presidential executive orders issued over the past 50 years, security classification policy and procedure provide the rationale and arrangements for designating information officially secret for reasons of national security, and for its declassification as well."
CRS Report for Congress, 97-771