“Sensitive Security Information (SSI) is information that would be detrimental to transportation security if publicly disclosed,” according to a Department of Homeland Security directive released last week under the Freedom of Information Act.
See DHS Management Directive 11056 (pdf), “Sensitive Security Information,” December 16, 2005.
Confusingly, however, SSI is also a control marking used by the Department of Agriculture to mean something quite different, observed information policy expert Harold C. Relyea of the Congressional Research Service in a new report (pdf) on classification and other information controls.
SSI “is both a concept and a control marking used by the Department of Agriculture (USDA), on the one hand, and jointly by the Transportation Security Administration (TSA) of the Department of Homeland Security as well as by the Department of Transportation, on the other hand, but with different underlying authorities, conceptualizations, and management regimes for it,” he wrote.
While the number of different designations for “sensitive but unclassified” information has been estimated at over 60, that number approaches 100 if different agency definitions of the same designation are taken into account, according to a Justice Department official.