Pub. L. 108-90, tit. V, sec. 521

Sec. 521. The Secretary of Homeland Security is directed to research, develop, and procure certified systems to inspect and screen air cargo on passenger aircraft at the earliest date possible: Provided, That until such technology is procured and installed, the Secretary shall take all possible actions to enhance the known shipper program to prohibit high-risk cargo from being transported on passenger aircraft.117 STAT. 1157