Millimetrix' millimeter wave passive imaging technology offers the opportunity for rapid and remote detection of metallic and non-metallic weapons, plastic explosives, drugs, and other contraband concealed under multiple layers of clothing without the necessity of a direct physical search. The purely passive imaging technique relies solely on the existing natural emissions from the scene objects, does not expose the person to any man-made radiation, and is therefore completely harmless to the person being observed and to all others in the area. Screening can be done remotely and with as much discretion as the situation requires. The passive imaging approach to the detection of concealed weapons and contraband hidden under people's clothing works well at millimeter wavelengths because of a fortunate convergence of a number of key factors: (1) adequate resolution in a reasonable sensor size; (2) high transparency of virtually all clothing; and (3) the extraordinarily high emissivity of human flesh compared to the vast majority of other materials. Longer (microwave) wavelengths are impractical because of sensor size and resolution issues, and shorter (infrared) wavelengths are impractical because of the poor transparency of most clothing. The ability of millimeter wave emissions to penetrate many common building materials permits the remote observation, using active millimeter wave sensors, of people and other objects within a room from outside of that room. The resulting through-the-wall 'live' video images of people and furnishings will indicate their location, posture, and activity within a room which should be valuable knowledge to Special Operations, SWAT, and other military and law enforcement personnel prior to their entering that room. Millimeter wave radar imaging systems based on passive MillivisionR camera technology are being developed by Millimetrix (and other members of the MIRTAC TRP consortium) for through-the-wall imaging system (TWIS) applications.