In purported efforts to help the public "understand the privacy risks of carrying a mobile phone," the ACLU and the EFF are suing the Justice Dept. for "documents, memos, and guides" about procedures used to track individuals through cell phones.

The American Civil Liberties Union and the Electronic Frontier Foundation aren't looking for money -- except to cover their own costs -- in their most recent lawsuit against the US Department of Justice. Instead, the two civil liberty advocacy groups want information about whether and how the government might be using the location capabilities in cell phones to find out where people are.

"Recent court decisions and media reports reveal that US Attorneys Offices (USAOs) are assisting law enforcement officers in obtaining information from mobile carriers that enables officers to track the location of individuals' mobile phones," the document says.

"Court decisions indicate that USAOs claim not to need probable cause to obtain real-time tracking information. News reports further suggest that some field offices are violating a Department of Justice 'internal recomendation' that 'federal procecutors seek warrants based on probable cause to obtain precise location data in private areas.'"

Filed in federal court in Washington, D.C., the lawsuit asks the DOJ to search several specific federal offices within the agency -- including US Attorneys' Offices in six states and the District of Columbia -- for records related to cell phone tracking.

The types of records sought in the suit pertain to policies, procedures, and practices used for obtaining mobile phone location information; the DOJ's "internal recommendation" and any violations of that recommendation; and the number of times the government has applied for a court order, based on less than probable cause, using that court order as authority to obtain mobile phone location information, "and whether such applications were successful."

In an appendix to the court document, the plaintiffs have attached a news article that mentions a couple of location-based services already offered by mobile providers for tracking people outside the realm of criminal justice. The two examples include Verizon Wireless' Chaperone service, aimed at helping parents to track their kids, and Sprint Nextel's "loopt" service, for "sending an alert when a friend is near."

It's important to note, though, that if carriers are enabling cellular tracking -- whether for parents, friends or law enforcement officials -- any location data they're obtaining really refers to the phone itself, as opposed to the mobile subscriber.

Many cell phone owners don't carry their phones with them at all times. People also lose and temporarily misplace their phones, and loan them to family members and even casual acquaintances. Consequently, a cell phone's location isn't exactly a solid indicator of the actual current location of the owner of that phone. So beyond any privacy risks, there could be risks, too, of mistaken identity.