Airport ‘Nude’ Body Scanners: Are They Effective?

David Kravets
March 8, 2011
http://www.wired.com/threatlevel/2011/03/scanners-part3

The body scanners rolling out to airports nationwide may violate travelers’ privacy, and they might even cause cancer.

But they prevent terrorists from wreaking havoc. Or do they?

Some research claims the machines — which produce a virtual nude image of the body — might not detect explosives or even guns taped to a person’s body. The U.S. government has reservations about their efficacy, as well. And even proponents of the technology concede the machines are not designed to detect so-called “booty bombs” — explosive devices concealed inside the human body.

“It’s not a possibility of the technology,” said Peter Kant, executive vice president of Los Angeles-based Rapiscan Systems, which has deployed 250 of its backscatter X-ray devices and another 250 are on the way. “None of the body scanners used by TSA are capable of doing that. They’re not designed to do that nor is it a requirement.”

Along with potential health issues, the efficacy of the so-called “advanced imaging technology” scanners will be a key issue Thursday when a high-profile lawsuit filed by the Electronic Privacy Information Center is heard by the U.S. Court of Appeals for the District of Columbia Circuit. EPIC is challenging the TSA, which last year began placing about 500 of the $180,000 machines in 78 airports nationwide. Hundreds more machines are to be deployed this year.

EPIC is seeking a court order to halt the use of the scanners, on the grounds that the devices pose a health danger, are ineffective and breach Americans’ constitutional right of privacy. Because Fourth Amendment questions tend to balance the privacy invasion against the government’s legitimate interest in performing it, the TSA will have to make the case that the scanners — introduced nearly a decade after the Sept. 11 attacks — are an important bulwark against future airline terrorism.

“The ultimate question under the Fourth Amendment is reasonableness,” said Ginger McCall, an EPIC attorney on the case. “If they’re ineffective and put people at a health risk, it’s going to be an unreasonable method.”

According to a heavily redacted TSA procurement directive EPIC obtained through the Freedom of Information Act, the TSA required that the devices detect explosives, weapons, liquids and “other anomalies.” Several studies, though, point to limitations in the machines.

The Government Accountability Office — Congress’ investigative arm — concluded in a report last year that AIT scanners might well not have found the explosives concealed in the underwear of Umar Farouk Abdulmutallab. The Nigerian tried to detonate plastic explosives on a flight to Detroit from Amsterdam on Christmas 2009. (He did not go through a body scanner in Amsterdam.)

“It is unclear whether the AIT or other technologies would have been able to detect the weapon Mr. Abdulmutallab used in his attempted attack,” the GAO wrote.

Kant disputes the GAO report, and says his Rapiscan scanners would have stopped the “Underwear Bomber,” who was ultimately thwarted by poor bomb design and alert passengers. “We feel very confident we would have detected that if he had gone through the system before boarding the plane,” Kant said.

New York-based L-3 Communications, the government’s only other body-scanner contractor, declined to be interviewed.

A study published in the November edition of the Journal of Transportation Security suggested terrorists might fool the Rapiscan machines and others like it employing the X-ray “backscatter” technique. A terrorist, the report found, could tape a thin film of explosives of about 15-20 centimeters in diameter to the stomach and walk through the machine undetected.

The L-3 machines use what is known as “millimeter wave technology” and were not the focus of the study.

The report said an explosive, such as pentaerythritol tetranitrate, “would be invisible to this technology, ironically, because of its large volume, since it is easily confused with normal anatomy.” The report found that “a wire or a box-cutter blade taped to the side of the body, or even a small gun in the same location, will be invisible.”

The TSA, though, says the technology is a significant improvement over metal detectors that failed to stop Abdulmutallab.

“While there is no silver bullet technology, advanced imaging technology is a highly effective security tool which can detect both metallic and nonmetallic threats, including weapons and explosives,” Sarah Horowitz, a TSA spokeswoman, wrote in an e-mail. “Using this critical technology, TSA routinely detects artfully concealed metallic and nonmetallic prohibited items.”

Horowitz added that the machines detected more than “130 prohibited, illegal or dangerous items at checkpoints nationwide since January of last year.”

Oral arguments in the lawsuit are scheduled for 9:30 a.m. EST on Thursday. Threat Level will cover the hearing from the courtroom.