The petitioners argue that using AIT for primary screening violates the Fourth Amendment because it is more invasive than is necessary to detect weapons or explosives,” the appeals court noted. “As other circuits have held, and as the Supreme Court has strongly suggested, screening passengers at an airport is an ‘administrative search’ because the primary goal is not to determine whether any passenger has committed a crime but rather to protect the public from a terrorist attack.”

The court said that, whether an administrative search is unreasonable, is a balancing test on how much it intrudes upon an individual’s privacy, and how much that intrusion is needed for the promotion of “legitimate” government interests. “That balance clearly favors the government here,” the court ruled 3-0.

The case is EPIC v. the Department of Homeland Security, Case No. 10-1157 (D.C. Cir. filed July 2, 2010). You can read the legal arguments and documents here.EPIC says its "core assertion" was:

"[T]he TSA has acted outside of its regulatory authority and with profound disregard for the statutory and constitutional rights of air travelers." EPIC asserts that the federal agency's controversial program violates the Administrative Procedures Act, the Privacy Act, the Religious Freedom Restoration Act, the Video Voyeurism Prevention Act, and the Fourth Amendment.

The Court today accepted only the Administrative Procedures Act Challenge.

Here is what TSA says is shown on the monitors by its Millimeter Wave and Backscatter Unit, which are the two types of AIT employed. Here is how the TSA says it protects your privacy.