This report formally transmits the attached briefing in response to section 1602(b) of the Implementing Recommendations of the 9/11 Commission Act of 2007. The act requires the Comptroller General to provide an assessment of the methodology used by the Secretary of Homeland Security for maintaining, changing or eliminating an exemption under 49 U.S.C. 44901(i)(1). We provided the mandated reporting committees with a restricted version of this briefing in July 2008. Based on the results of our review, we are not making any recommendations for congressional consideration or agency action. All information considered Sensitive Security Information by the Transportation Security Administration has been removed from this product.