A federal appeals court on Thursday appeared unlikely to block the use and ongoing deployment of the so-called “nude” airport body scanners, which the government maintains are necessary to protect the airways from terrorists.

Still, the US Court of Appeals for the District of Columbia Circuit, which hears challenges to Department of Homeland Security policies, did not indicate during an hour-long oral argument here whether it agreed with allegations that the machines are an unconstitutional privacy invasion, ineffective, and unhealthy. Instead, the three-judge panel, which did not indicate when it would rule, appeared stuck in the procedural muck, and spent little time on those bread-and-butter issues.

The judges focused the bulk of the session on whether the government violated federal rules by not allowing a public-comment period before Homeland Security adopted the scanners in 2009 as the preferred airport screening method. None of the judges said outright that such a requirement was necessary.

Forcing the government to accept and respond to public input would thwart its ability to respond to “ever-evolving threats,” Justice Department lawyer Beth Brinkmann told the judges.

Marc Rotenberg, the executive director of the Electronic Privacy Information Center, which brought the case, urged the judges to order the government to stop using the scanners and take public input.

That didn’t sit so well with Judge David Tatel.

“I get your point,” Tatel told Rotenberg.

Tatel wondered aloud whether the circuit’s precedent even came close to requiring public input. He asked Rotenberg to cite his best local circuit case to bolster his position. Laughter from the roughly 60 suited government and private attorneys erupted after Tatel quipped that Supreme Court precedent would work, too.

“I’ll accept that,” he said.

Generally, under the Administrative Procedures Act, government agency decisions must go through what is often termed a “notice and comment” period if their new rules would substantially affect the rights of the public—in this case air passengers. The Environmental Protection Agency often undertakes “notice and comment” periods for proposed pollution regulations.

Tatel wondered aloud whether the government would have to seek public input if the TSA began literally strip-searching fliers because a “terrorist gets through and blows up the airport.”

“No,” Brinkmann answered.

Congress, she added, required transportation officials to use the scanners or “effective technology” to protect the airlines, so no public input was necessary.

“You may well be right,” Tatel responded.

Moments later, Brinkmann added: “You can’t hamstring the agency.”

She added that the government is moving toward adopting new technology that produces a broad outline of a passenger instead of a virtual nude image. What’s more, passengers may opt for a pat-down instead of going through the machines, which are deployed to at least 78 airports nationwide. More airports are planned.

Judge Douglas Ginsburg at one point expressed alarm that there might not be adequate signage informing people of the right to opt out. And he mocked the government for initially declaring its signage policy a non-public record.

“Is there a secret handshake?” he quipped. The gallery, again, laughed.

Jokes aside, Ginsburg told Rotenberg that the Transportation Security Administration is addressing the signage problems.

“You asked them to put up signs and they did,” Ginsburg said.

Brinkmann said that the invasiveness of the pat-downs have changed over time. Some fliers have recently complained that they felt as though they were being sexually groped.

The government’s attorney also argued that, because the scanners were not mandatory, they did not violate passengers’ Fourth Amendment right of privacy.

Ginsburg seemed to agree.

“No one is coerced into doing the full-body scanner,” he said.

Rotenberg, however, objected to the pat-downs.

“This is not a meaningful option,” he said.

Brinkmann said an “infinitesimal percentage” of passengers had complained about the pat-downs.

Meanwhile, Judge Karen Henderson was the only judge to broach the topic of whether the machines are unhealthy to fliers, especially those who travel a lot.

“Have you considered the frequent flier?” Henderson asked Brinkmann. “That’s a lot of radiation.”

Brinkman said radiation levels were “minimal” and “extensive studies” were conducted.

A Wired.com three-part series on the body scanners concluded that there was not agreement in the scientific community about the safety of the machines.

The government maintains that a flier would have to go through one of the so-called “backscatter” X-ray machines 1,000 times to equal one standard medical X-ray. But some scientists said there has been no testing of the machines on mice or other biological material, and they maintain radiation levels are higher than stated.

During Thursday’s arguments, the judges did not discuss the effectiveness of the machines—now numbering 500 and growing.

Some research suggests that the machines might not detect explosives or even guns taped to a person’s body. The US government has reservations about the efficacy of the machines that cost about $180,000 each.

Even proponents of the technology concede the machines are not designed to detect so-called “booty bombs”—explosive devices concealed inside the human body.