Beyond United States v. Jones: The Absolute Mosaic & The Inverted Fourth Amendment

Sunday, April 21, 2013, by Ken Jennings

The Mosaic Theory of the Fourth Amendment has featured front-and-center in the continuing debate over the impact of the Supreme Court’s decision in United States v. Jones.  In Jones, law enforcement officials tracked the location of the defendant’s (borrowed) vehicle for 28 days via a GPS device installed outside the scope of a valid warrant.  The D.C. Circuit leaned heavily on a reasonable expectation of privacy rationale to find in favor the defendant, planting the seeds of the Mosaic Theory.  They stated that prolonged GPS surveillance, “reveals types of information not revealed by short-term surveillance, such as what a person does repeatedly, what he does not do, and what he does ensemble.”

A Scalia-led majority upheld the D.C. Circuit based on a rediscovered theory of invasion-by-trespass, largely avoiding discussion of mosaics.  Alternatively, some scholars have emphasized the Mosaic Theory in the Jones concurrences.  In a soon-to-be-published paper (NC Journal of Law and Technology, Volume 14 Issue 2) Priscilla Smith argues that the concurring Justices’ approach is more subtle.  Rather than being concerned with the effects of aggregation, Smith reads the concurrences as describing concern for the ease with which new technologies capture information that has previously been too expensive for law enforcement to obtain.  In either reading, it is clear that at least four members of the Supreme Court are worried about Fourth Amendment protections in this brave new world.  This article considers one extreme hypothetical, in the hopes of testing the Mosaic Theory and perhaps divining a better understanding of the Fourth Amendment.


The Absolute Mosaic


Suppose that the technology of today could instantly be advanced by roughly 25 years.  Imagine a world where all the data that people so haphazardly share on social networks, including demographics, personal interests, relationship status, and location, are passively collected.  Furthermore, practically everything you interact with on a daily basis now includes an embedded computer: books, magazines, movies, smart surfaces (tables/walls); your eyeglasses, your refrigerator, your car.  The computer science concept of ubiquitous computing lends some credibility to this fiction.  The sum total of all this information processing power is a perfect record of your activities.  This absolute mosaic has no holes; the spacing between tiles is practically nonexistent.

Now imagine that law enforcement has the means to access that record.  Assume, for simplicity, that accessing the data does not constitute a trespass in any traditional sense of the word.  Would the Fourth Amendment, as we know it, prohibit warrantless access to some/all/none of this information?  Records of activities taking place in the home would clearly fall under Fourth Amendment protection.  Likewise, records of activities in overtly public places (reading a book in a coffee shop), where no reasonable expectation of privacy exists, would not be protected.  Thus the answer is arguably that some of the information stored in such a system should be openly accessible to law enforcement.

It is interesting that, in such a world, the Fourth Amendment is inverted.  Rather than pro-actively preventing the collection of protected information, it becomes a filter.  For example, when a police officer queries the system for an individual’s information without a warrant, it would need to remove from its report any records collected at that individual’s home or other “constitutionally protected areas.”  The result could be visualized as a set of more-or-less arbitrarily defined circles on a map, within which records of your activities are protected by the warrant requirement.  That protection might provide meager comfort.  For many individuals, a large majority of their daily activities would occur outside of those circles.  Where law enforcement has uninhibited access to 99% of your reading habits, for example, it becomes trivial to deduce what you are reading in the privacy of your home.

It seems clear that such pervasive collection of personal information would have a chilling effect on personal activity, which Ms. Smith points out as a principle concern of the concurring Justices.  Even if societal attitudes towards privacy shift drastically to acceptance of pervasive collection, however, the Mosaic Theory would offer pause.  At least where the Mosaic is sufficiently complete, the aggregate effect of information collected in non-protected areas threatens individual privacy even in locations where the Fourth Amendment unequivocally applies.