Q. What does a chief privacy officer do?

"Thankfully, these requests don't come up that often," Jonathan Cantor, the privacy officer at the agency, said.

He said having a privacy officer could ensure that the department considered alternatives that might be less intrusive.

Mr. Barr said he would seek to amend the legislation to provide for a privacy officer.

Earthlink, the second-largest Internet service provider, has joined a growing crowd of companies that have appointed chief privacy officers.

The privacy officers themselves describe their jobs as a work in progress.

At companies for which privacy is the core business, the role of chief privacy officer is especially crucial.

These include the appointment of what they regard as an independent privacy officer to hear complaints from European citizens.

To that end, the company announced that it is promoting two members of its legal staff to serve as "chief privacy officers."

Lisa S. Dean, the agency's privacy officer, said under the proposed system, "we're not looking for every passenger as a potential terrorist."