DHS and TSA share responsibility for the research, development, and deployment of passenger checkpoint screening technologies. The Aviation and Transportation Security Act established TSA as the federal agency with primary responsibility for securing the nation's civil aviation system, which includes the screening of all passengers and property transported to, from, and within the United States by commercial passenger aircraft. Additionally, the Homeland Security Act of 2002 established DHS and, within it, the Science and Technology Directorate for, among other things, conducting research, development, demonstration, and testing and evaluation activities relevant to DHS. DHS's Science and Technology Directorate is responsible for testing and evaluating aviation security technologies, including AIT systems, at the TSL on behalf of TSA.