From EPIC.org:
New documents obtained by EPIC under the Freedom of Information Act provide further details on a DHS plan to use an multiples surveillance technologies to search people in public spaces. Previous EPIC FOIA work produced records about a similar DHS program, which the government agency subsequently claimed it had cancelled. However, the new documents obtained by EPIC show that the DHS was still pursuing mobile crowd surveillance as recently as 2011. The technologies include “intelligent video,” backscatter x-ray, Millimeter Wave Radar, and Terahertz Wave, and could be deployed at subway platforms, sidewalks, sports arenas, and shopping malls. For more information, see EPIC: EPIC v. DHS (Mobile Body Scanners FOIA Lawsuit) and EPIC: Electronic Frisking