Controversy over revelations regarding iPhone and iPad location tracking has been growing quickly. As the New York Times reports, the German, French, and Italian governments have either started or will soon start investigations into whether the tracking violates those countries’ respective privacy laws. In the United States, Senator Al Franken of Minnesota and Congressman Edward Markey of Massachusetts have sent letters asking for further explanation from Apple.

A letter from Apple’s general counsel to Congressman Markey last July suggests that the data is in fact being transmitted to Apple for use in its location-based services. However, the letter indicates that location data is anonymized and only collected when users agree to use location-based services. Last Friday, Google confirmed that it collected similar data from Android users for similar location-based service purposes, again anonymized and with user consent.

Some commentators have questioned the need for retaining the location data on users’ devices, arguing that it leaves them vulnerable to hackers who would be able to learn a user’s day-to-day movements. Others question whether users are fully informed about the extent of location tracking due to the sometimes-vague and difficult-to-understand privacy policies that describe its use.

The New York Times article also reports that the data has been used for law enforcement purposes, raising interesting questions about the applicability of the Stored Communications Act and the 4th Amendment to such data. Though the article doesn’t specify the legal basis upon which law enforcement gathered this data, it seems possible that the SCA would apply. Would a court hold that compelling Apple to produce such data under the SCA but without a warrant violates the 4th amendment, much like the compelled e-mail production in United States v. Warshak? On a related note, the ACLU recently reported that Michigan State Police officers have been using forensic cellphone analyzers to download the contents of smartphones during routine traffic stops. The ACLU has issued a FOIA request for more information on this practice, but the Michigan Police have requested over $500,000 from the ACLU to cover the costs of retrieving and assembling such documents. Given the recent revelations about location tracking on Apple products it seems plausible that such data collection from Apple users could include the location-tracking file, thus possibly giving the police information about the user’s every move for the past few months.