Currently, classification and declassification of U.S. government information is governed by Executive Order 13526, Issued by President Barack Obama on December 29, 2009.

Declassified, as well as currently classified, government information can be an important source for understanding U.S. policy. (Much of the classifed information leaked by Pvt. Bradley -- now Chelsea -- Manning and Edward Snowden remains classified, even though it is now readily available.)

The purpose of this guide is to facilitate access to classified and declassified government information in Pitt's library system or on the Web.

 Approval of program against Salvador Allende of Chile, March 25, 1970. Source: CIA

Executive Order 13526 defines "classified information" as "information that has been determined ... to require protection against unauthorized disclosure ..."

The order explains that government information can be classified only if "the original classification authority determines that the unauthorized disclosure of the information reasonably could be expected to result in damage to the national security, ... and the original classification authority is able to identify or describe the damage."

This order describes five methods for the declassification of government information:

• Whoever has classified a piece of information may declassify it when the reason(s) for its classification no longer hold.
• One agency can challenge another agency’s classification of information.
• Automatic declassification occurs after 10 years, with exceptions that permit continuing classification for 25 or 50 years.
• Systematic declassification review is for documents exempted from automatic declassification.
• Mandatory declassification review -- like FOIA requests-- may be sought by a member of the public.

In addition to these methods, documents may be declassified by a Congressional statute, or in response to  Freedom of Information Act  (FOIA) requests.