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Electronic Frisking (Terahertz Wave Technology)

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Technical Capabilities

Terahertz waves sit on the electromagnetic spectrum between microwaves and infrared and can be applied to "see" through solid barriers and identify materials, even in trace amounts. In 2010, a research breakthrough discovered how to use Terahertz technology at a distance of up to 67 feet. The researchers theorized that it would be possible to "identify materials hundreds of feet or even miles away." This research was funded primarily by the Department of Defense and the Department of Homeland Security.

Jingle Liu, the lead physicist on the project, which was run by Rensselaer Polytechnic Institute through Northeastern University, described the technology:

Two lasers at different frequencies aimed at the target together generate a plasma (basically excited, or ionized air). This plasma emits a florescence that is scattered in characteristic ways by the terahertz radiation of the material it hits. The reflection of the florescence is detectable from remote distances.

The Terahertz waves detect a unique "fingerprint" that every substance carries, and can determine exactly what compound or compounds are being carried in packages, boxes, clothing, shoes, or backpacks. The researchers at Rensselaer have already started compiling a "library" of substance fingerprints. The technology does not work through liquid or metal.

The new terahertz technology is currently being tested at a Police shooting range in the Bronx. Police spokesman Paul J. Browne told the New York Times that the technology is currently effective at three to five meters, and that the goal is to get it to work at up to 25 meters away from an individual.

EPIC has previously obtained documents from the Department of Homeland Security ("DHS") about the Department's development of mobile body scanner and crowd surveillance technology. The documents detailed the Department's use of equipment to scan crowds and pedestrians on the street. The documents reference the development of Terahertz technology and refer to it as "cutting edge"

Privacy Issues

The Fourth Amendment protects individuals from "unreasonable searches and seizures." Terahertz Wave gives law enforcement and government officials the ability to conduct a search of any individual without the individual's knowledge or consent. These "secret searches" are likely to diminish accountability. In addition, the effectiveness of the Terahertz technology is unproven. The technology may be used to pick up even trace amounts of chemicals, meaning that an individual could come under suspicion for something inadvertently encountered on a public surface, and that could be used to subject that individual to further interrogation and searches.

In New York City, where this technology is being developed to assist law enforcement, the police department has already come under scrutiny for the overuse and inappropriate use of the "stop and frisk" program.

Administrative Filings

Freedom of Information Act Documents

DHS' First Production of Documents

DHS' Second Production of Documents


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