The Transportation Security Administration has installed about 500 full-body scanning machines at airports across the country, with plans to buy and operate about 500 more this year. The agency first began deploying the machines in 2007, but it significantly ramped up their use last year after a Nigerian man unsuccessfully tried to blow up an airliner over Detroit using explosives material sown into his underwear.
Critics argue that the machines invade passengers' privacy because they produce an image of a person's body without clothes. Concerns have also been raised that the machines put out unsafe levels of radiation.
Leahy identified the use of the machines as an issue he wants the Judiciary Committee to review.
"The committee will also examine several emerging privacy issues that are of growing concern to me and many Americans, including the invasive full-body screening at our airports and the tracking of Americans' activities online," he said in outlining his oversight agenda.
A Judiciary spokeswoman said on Friday that it was too early to provide details on what Leahy plans to do. "The Judiciary Committee certainly has great interest in privacy issues, and that was the context in which he was speaking," she said.
During a speech this week, Leahy said that the government must strike a balance between defending the country from terrorist attacks and protecting the constitutional rights of U.S. citizens.
"Do we want to be safe? Of course we want to be safe. Do we want to protect ourselves? Of course we do. Do we want to protect our liberties? Of course we do. But let's be honest: It is going to take work to have that balance," he said.
"Today, we need care and foresight because we continue to face the threat of terrorism and violence," Leahy added. "A government of the people, by the people, and for the people must be accountable to the people. We need a commitment to vigorous oversight and government transparency."
TSA defended the use of the machines in a statement, saying the agency has been upfront in providing public information on their use and what kind of safeguards are in place to protect people's privacy.
For example, the airport screener who views an image of a passenger does so in a room walled off from that person and never sees him or her. TSA also maintains that the machines cannot store or transmit the images.
"The agency continues to research technology that balances privacy concerns with security needs, and is currently exploring additional privacy protections for this technology," TSA said in its statement.
"Since 9/11, Congress has mandated that TSA develop and deploy technologies that mitigate threats to transportation," the statement continued. "While there is no silver-bullet technology, this vital technology is a highly effective security tool which represents the best available technology to safely screen passengers for metallic and nonmetallic threats, including weapons, explosives, and other objects concealed under layers of clothing."