The choice is really quite simple: a blast of radiation or a groping of the genitals...

Airline passengers don't have a right to refuse security screening after placing carry-on bags on conveyor belts at airport checkpoints, according to the Transportation Security Administration.

It doesn't matter if a person worries that body scanners emit radiation or produce graphic images, or considers the alternative -- a pat-down search -- as too hands-on.

Those were among objections a California man gave when he refused to be screened Saturday in a San Diego airport. The man opted to turn around and go home but said he was threatened with legal action as he left the checkpoint area.

The TSA on Monday defended its actions, touching off arguments among travelers and legal experts.

Body scanners "safely screen passengers for metallic and nonmetallic threats to help keep the traveling public safe," said spokeswoman Ann Davis. Such screening is optional, she said, but passengers who decline must undergo alternate screening that includes "a thorough pat-down."

Independent studies showed radiation from the screeners does not present a risk, Davis said. Some pilots are concerned about cumulative effects if they pass through a scanner several times a day and several days a week, said Sam Mayer, a Boeing 767 captain and spokesman for the Allied Pilots Association.

The agency's representatives two weeks ago started using their palms and fingers to probe for hidden weapons and other devices in pat-down searches. In the past, screeners used the back of their hands to brush past sensitive body parts.

Anyone who refuses screening would be subject to civil penalty, Davis said, in addition to being denied access beyond a security checkpoint or onto a flight. She couldn't say whether the agency fined anyone for refusing to be screened, but she said less than 1 percent of passengers require pat-down searches. The TSA has 300 full-body scanners operational in 60 U.S. airports, including five in Pittsburgh, and will deploy more...