Academic journal article Harvard Law Review

Data Mining, Dog Sniffs, and the Fourth Amendment

Academic journal article Harvard Law Review

Data Mining, Dog Sniffs, and the Fourth Amendment

Article excerpt

An algorithm, designed to probe a database containing all personal data available to the government, sees that you have recently bought some fertilizer and a large truck, and that you have emailed someone with a .lb (Lebanon) email address. Seeing this red flag pop up on his computer, a government agent pulls your bank records, your Amazon and iTunes purchases, the domain names that you've recently visited, and a list of everyone you have recently phoned or emailed. Inspecting all of these records, the agent determines that you were merely asking your Lebanese uncle for advice on expanding your farm and makes a notation in his database. (He is also able to determine your religious affiliation, that you have an affinity for Steven Seagal movies, and that you have been having an affair, but is less interested in all of that.)

This example of "data mining" is the future, if not the present, of law enforcement. (1) Data mining both offers enormous possibilities for law enforcement and national security--in the scenario above, the fertilizer and truck could have been intended for a far less innocuous use--and radically undermines the notion that one's interests, affiliations, and legal activities can be kept private from the government. Such concerns have led to significant public debate over the proper scope of surveillance, prompted in particular by Edward Snowden's recent disclosures.

Yet despite the obvious privacy implications of data mining, traditional Fourth Amendment doctrine offers relatively little to help constrain such activity. The Supreme Court has held that one cannot have a reasonable expectation of privacy in information that is given to third parties (2) or made accessible to the public. (3) In the modern era, this doctrine covers an enormous amount of activity: commercial interactions are known to credit card companies; (4) financial records are in the hands of banks; (5) phone calls and emails entail offering telecommunications companies the numbers and addresses necessary to route the information properly; (6) and even a cell phone's location may be known to the phone company at all times. (7) Such information, under extant Supreme Court doctrine, arguably falls outside the scope of the Fourth Amendment's protections. Accordingly, the government can compile and analyze it largely free from constitutional scrutiny. (8)

Commentators have responded to this apparent deficiency by suggesting that individual sources of information might be protected, Facebook and other social networks being one widely debated example. (9) But the reality of modern data mining is that removing isolated sources from the flood of "public" information will do little to stop the government from divining a detailed portrait from the information that remains available. Whatever restraints are imposed on the collection of individual sources, it continues to be true that "most government data mining today occurs in a legal vacuum outside the scope of the Fourth Amendment and without a statutory or regulatory framework." (10)

Taking another tack, five Justices of the Supreme Court have signaled a willingness to move away from the piece-by-piece analysis toward a "mosaic theory" of the Fourth Amendment. (11) In United States v. Jones, (12) the majority decided that long-term surveillance via a GPS beacon attached to a car bumper constituted a search due to the physical trespass upon the bumper. (13) Yet Justice Sotomayor concurring and Justice Alito--joined by Justices Ginsburg, Breyer, and Kagan--concurring in the judgment suggested that the collection of sufficiently large amounts of information might amount to a search (thus implicating the Fourth Amendment) regardless of physical trespass. (14) However, the question as framed in Jones--to what degree a given type of information can be analyzed--is likely to offer little guidance to courts struggling to determine the validity of investigations using multiple types of rapidly evolving information-gathering techniques. …

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