My friend Jen Urban of UC Berkeley and her colleagues Chris Jay Hoofnagle and Su Li have just published Mobile Phones and Privacy, a paper in the BCLT Research Paper Series, and a summary. In a nutshell, people totally overestimate the privacy of the data on their mobile phones, they oppose all the current legislative directions on mobile privacy, including the ability of the police to plunder their phones for "suspicious" information and the practice of carriers retaining detailed logs of their activity.

We've just released another tranche of data from our 2012 consumer privacy survey. This one focuses upon privacy issues surrounding mobile phones. As with our other studies, this is a telephonic (landline and wireless) survey of Americans with a sample size of about 1,200 people. Some highlights:

We asked consumers whether they thought information on their mobile phones was private in three different ways:

* A large majority—78%—of Americans consider information on their mobile phones at least as private as that on their home computers. Fifty-nine percent consider it "about as private" and 19% consider it "more private." Those under 45 were more likely than those over 45 to respond that data on phones was more private than data on home computers.

* A large majority rejected the idea that law enforcement should be automatically able to search a cell phone of someone who is arrested. 76% supported requiring officers to get permission from a court prior to searching a mobile phone in this situation.

* We asked consumers whether they would be willing to lend their phones to others. While most would lend it to a spouse or close friend, most would not lend their phone to an acquaintance or work colleague. When we probed for explanations, privacy rationales dominated the resistance to lending the phone to others.

In addition to determining individuals expectations around privacy, we asked a number of specific questions about business practices:

* A large majority objected to the basic premise behind the established business relationship. 74% said that businesses that they frequent should not be able to call them, even if the consumer provides the cashier with her phone number.

* We asked about the information practices of apps and found rejection of common business models. 81% of respondents said they would "definitely not allow" (51%) or "probably not allow" (30%) sharing contact lists in order to receive more connection suggestions.

* Americans support strong limits on data retention in the wireless context. 46% answered that wireless phone location data should not be kept at all. The next largest group—28% of respondents—answered that the data should be kept less than a year.