The American Civil Liberties Union (ACLU) has found that officers routinely use phone location data when pursuing cases, often without a warrant. Carriers, however, don't give tracking or other information out for free. Forbes has reviewed a 2009 document that apparently instructs Tucson, Arizona police on how much AT&T, Verizon, Sprint, T-Mobile, and others charged at that point for everything from wiretaps to voicemail.

AT&T, for example, charged $50 an hour (with a $200 minimum) for a "tower dump," which would disclose who had been using all towers in a particular area and timeframe. Other companies had similar prices listed, with the exception of Cricket, which apparently refused to provide information for anything but specific names and numbers. Here are some more standout bits:

• Wiretaps or traces generally cost between $375 and $500 to activate, sometimes with an additional per diem fee of $10 for 30 days.
  In some cases, voicemail cost extra to retrieve: Sprint, for example, puts it at $60.
• Sprint and Verizon offered to retrieve both picture and SMS content for a fee; T-Mobile apparently did not store this information, and AT&T did not provide a cost breakdown.
  VoIP services like Skype and Vonage were listed in the document, but all pricing information was blank.
• Most carriers offered automated tracking tools for location data; these cost between $30 a month and $100 a day.

AT&T declined comment, but Verizon has told Forbes that it doesn't charge police in "emergency cases, nor do we charge law enforcement for historical location information in non-emergency cases." Sprint likewise said that it did not charge in "exigent circumstances," and that "any fee charged is for recovery of cost required to support these law enforcement requests 24 / 7." T-Mobile indicated a line in its privacy policy: "We do not sell your personal information to anyone for any purpose. Period."

That claim, says ACLU lawyer Catherine Crump, is "simply misleading... given that they seem to be charging money for people’s information on a regular basis and handing it over to law enforcement agencies around the country." It's important to note that in cases where police obtain a warrant, companies may have little choice in turning over information. But with cellphones serving as communication, storage, and tracking devices all in one, it's important to clarify just how far carriers and law enforcement can go in requesting and selling it.