House Judiciary Committee Chairman John Conyers (D-MI) sent letters on Friday to Facebook and Google asking them to respond to privacy concerns that have arisen in connection with their services.

The Judiciary Committee is considering whether to hold hearings that could result in legislation regulating electronic communications and online security. The Federal Trade Commission is already looking into the privacy policies of Facebook and other social networks, however, and it is not clear whether Conyers intends to launch his own investigation.

The letter (pdf) to Facebook CEO Mark Zuckerberg asks for "a detailed explanation of the information about Facebook users that your company has provided to third parties without the knowledge of the account holders." It also requests that he "detail how the new policies Facebook is adopting differ from past practices, including whether the burden is on the user to opt in or out of the relevant privacy settings."

According to the Associated Press, a Facebook spokesperson "said the company looks forward to meeting with Conyers' staff to explain its privacy practices and policies."

The Judiciary Committee's concern over Google involves its recent admission that the "Street View" cars which it sends out to map the locations of wireless access points have also been capturing private data sent over those networks. Conyers' letter (pdf) to Google CEO Eric Schmidt asks the company to retain that data while preventing its further dissemination pending review.

It is Facebook, however, that poses the trickier set of problems. Facebook's privacy protection policies have gradually grown weaker since its founding in 2004, and the latest wave of concern was triggered by a new "instant personalization" program designed to share user information with other online services.

Over the last two months, a number of prominent Internet figures, including Gizmodo co-founder Peter Rojas, have made a point of announcing that they were deleting or deactivating their Facebook accounts. Perhaps ironically, a number of Google software engineers were among them.

Facebook has now made changes that provide users with a greater ability to customize their profiles, but the result is unlikely to prove satisfactory to anyone who is seriously concerned about online privacy. As longtime Internet expert Wendy Grossman explains at net.wars, the default settings still provide for extensive sharing of information and users have to choose to opt out rather than choosing to opt in.

Despite this, Grossman concludes, any major changes appear unlikely. For one thing, the vast majority of users find Facebook a convenient way to stay in touch with friends and family and are not deeply concerned with privacy issues. For another, Facebook's business model depends on selling user data in order to support its free service.