Congress on Thursday will again grill executives from Apple and Google over mobile privacy concerns.
The hearing before the Senate Commerce committee will be the second in as many weeks, following one held by the body's Judiciary Committee on May 10 that took testimony about location tracking from both companies.
Thursday's hearing, called by the Communications, Technology, and the Internet subcommittee, will also question Facebook.
According to an announcement by Sen. Jay Rockefeller (D-WV), who chairs the Commerce committee, Catherine Novelli, Apple's vice president of worldwide government affairs; Bret Taylor, the CTO of Facebook; and Alan Davidson, Google's director of public policy, are to appear.
Officials from the Federal Trade Commission (FTC), the Association for Competitive Technology trade group, and Common Sense Media, a consumer digital protection advocacy group, are also slated to speak.
As at the May 10 hearing led by Sen. Al Franken (D-Minn.), this week's will dig into consumer privacy on mobile devices, particularly smartphones.
In that hearing, where Google's Davidson also testified -- Apple sent a different executive, Bud Tribble, the firm's vice president of software technology -- both companies denied that they tracked users' locations, claims that Franken said conflicted with other statements.
Congress jumped into the privacy issue after a pair of British researchers revealed that the iPhone 4 concealed an unencrypted file containing thousands of location data entries going back almost a year. The unsecured file was also backed up on users' PCs and Macs during synchronization.
A week later, Apple said it was not tracking users, but that the data was simply harvested-from-users information of cell tower and Wi-Fi networks positions. The data is used to pinpoint the phone's physical location faster than can GPS.
Although Facebook does not produce a mobile operating system, the powerful social networking site has been regularly criticized for its lax privacy controls, most recently last week when Symantec security researchers called out Facebook for leaking personal information of nearly 100,000 users to advertisers and others.
Facebook denied it had spilled details of its users.
Facebook is also fighting a California privacy bill that would ensure social networking services to require users set up their privacy settings when they first register.
This week's Senate hearing will start at 10 a.m. ET. Sen. John Kerry (D-Mass.) chairs the subcommittee.
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