Senator Al Franken (D-MN) has once again sent a letter (PDF) to Apple and Google, this time asking for a followup on the companies' app store privacy policies. In the letter, Franken reiterates some of the discussion that took place during a hearing in front of the Senate Judiciary Subcommittee on Privacy, Technology and the Law in early May, and asks that both companies commit to requiring all applications to have their own clear policies.

"Unfortunately, neither of your companies requires that apps on your stores have a privacy policy. As a result, a significant portion and potentially a majority of apps on your stores lack privacy policies," Franken wrote. "Requiring that each app in your stores has a clear, understandable privacy policy would not resolve most of the privacy concerns in the mobile market. But it would be a simple first step that would provide users, privacy advocates, and federal consumer protection authorities a minimum of information about what information an app will access and how that app will share that information with third parties."

Franken had originally called the Senate hearing after the location tracking controversy that first exploded over Apple's products and Google soon thereafter. The hearing was primarily meant to address mobile privacy on smartphones, tablets, and cell phones, and to get answers from Google and Apple about how and why they record various aspects of consumer data. During the discussion, Apple VP of Software Technology Guy "Bud" Tribble implied that the company's App Store developers were generally covered by Apple's general privacy policy for iTunes, but that wasn't what Franken wanted to hear.

Franken pointed out that numerous apps on both Apple's and Google's platforms had transmitted some kind of user data to third parties without users' knowledge, and asked that both companies begin requiring developers to post their own privacy policies for each app.

This week's letter is a followup to that request, showing that Franken means business when dealing with mobile privacy issues. The Senator did not, however, give the companies an explicit deadline to meet his request—instead, he's apparently hoping that they'll either comply or continue the discussion on how to better protect user information.

"Apple and Google have each said time and time again that they are committed to protecting users' privacy," Franken concluded. "This is an easy opportunity for your companies to put that commitment into action."