Classification protects national security information — but it is meant to be temporary. Declassification is the process of removing that protection when it is no longer warranted. Under Executive Order 13526, overseen by the Information Security Oversight Office (ISOO), there are three main pathways by which classified records are released.
1. Automatic declassification
The default rule for most classified records of permanent historical value is automatic declassification: when they reach a certain age — generally 25 years — they are automatically declassified unless a specific, narrow exemption applies. This pathway is what steadily opens the historical record to the public, and it places enormous review demands on agencies as large volumes of records reach the 25-year mark each year.
2. Mandatory declassification review (MDR)
Mandatory declassification review lets any member of the public request that an agency review a specific classified record for declassification. The agency must review the record and release whatever no longer requires protection. MDR is a focused alternative to a FOIA request and is often used by researchers seeking particular documents.
3. Systematic review
Systematic declassification review is an agency’s own ongoing program for reviewing classified records of permanent value before they hit the automatic deadline. It lets agencies manage the workload proactively rather than facing a cliff of overdue reviews.
The role of equities
A major complication is equities: a single record may contain classified information originated by more than one agency. An agency cannot unilaterally release another agency’s information, so records must be referred to all interested parties for concurrence. Managing these referrals across many agencies and millions of pages is one of the hardest logistical problems in declassification.
Marking and redaction
Throughout, reviewers redact information that remains sensitive while releasing the rest. Sound recordkeeping — accurate classification markings and an intact chain of custody maintained over decades — is what makes this review possible. Learn more on the declassification and FOIA and public records topic hubs.
Sources & further reading
Authoritative government and non-profit references.
- Information Security Oversight Office (ISOO) — National Archives (NARA)
- Executive Order 13526 — Classified National Security Information — National Archives (NARA) / ISOO
How to cite this page
APA
RM University Editorial Team. (2026). How Declassification Works: Automatic, Mandatory, and Systematic Review. Records Management University. https://www.recordsmgmt.org/articles/how-declassification-works/
MLA
RM University Editorial Team. "How Declassification Works: Automatic, Mandatory, and Systematic Review." Records Management University, 2 April 2026, www.recordsmgmt.org/articles/how-declassification-works/.