Federal regulations give the Transportation Security Administration (TSA) the power to issue Security Directives (SD) in response to threats against civil aviation. These SDs prescribe procedural or policy changes designed to address the specific nature of the threat, and differ from typical federal rulemaking in that they can be issued with no public notice, comment or cost-benefit analysis. In fact, SDs are typically considered Sensitive Security Information, thus limiting their distribution to directly regulated entities and/or individuals that the TSA determines have a “need to know.” In December 2008, the TSA issued an SD to the directors of airports serving commercial air carriers. This SD mandated changes to the issuance of airport identification media and expanded the base of individuals who would be required to obtain airport identifications.