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Cyber Law, Tech and Policy

General Interest

Surveillance: the “Sieve Theory” v. the “Mosaic Theory”

The Government Thinks It’s Legal to Access Your Emails. This Theory Explains WhyJane Chong at The New Republic:

“[T]he “sieve theory”: the idea is that the filtration techniques the government applies to extract certain pieces of data should have implications for the legality of the initial acquisition of a much larger dataset to which the government would not otherwise be entitled. The sieve theory is kind of the converse of a much-better-understood theory of the Fourth Amendment. The “mosaic theory,” as Fourth Amendment scholar Orin Kerr has dubbed it . . . That theory posits that many otherwise-insignificant and disparate data points can be combined to yield a highly revealing—and unconstitutionally invasive—composite. Like the mosaic theory, the sieve theory is built on the idea that constitutional protections do not attach to information per se but rather hinge on how that information gets processed and used. Just as privacy proponents use the mosaic theory to argue that bits of information not individually entitled to constitutional protections might be entitled to protections when aggregated, the government is effectively using the sieve theory . . . . . to argue that a large data set comprising information to which it might normally not be entitled should be produced anyway where the government both establishes its necessity and institutes satisfactory filters to prevent its misuse. Put more simply, the mosaic theory has been used to argue the unconstitutionality of certain types of government data collection. Conversely, the sieve theory is being used to argue the lawfulness of carefully conducted government data filtration.”

More on the mosaic theory: Professor Orin Kerr‘s (GW Law School) law review article, “The Mosaic Theory of the Fourth Amendment,” 111 Mich. L. Rev. 311 (2012).

10/16/2013: 

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Cyber Law, Tech and Policy

“[A] structural approach, which focuses on preserving an overall balance between state control and citizen autonomy, seems to me more appropriate for evaluating mass surveillance programs such as the NSA’s … . [T]he appropriate question is whether the creation of a system of surveillance perilously alters that balance too far in the direction of government control, whether or not we have problems with the current use of that system. We might imagine a system of compulsory cameras installed in homes, activated only by warrant, being used with scrupulous respect for the law over many years. The problem is that such an architecture of surveillance, once established, would be difficult to dismantle, and prove too potent a tool of control if it ever fell into the hands of people who—whether through panic, malice, or a misguided confidence in their own ability to secretly judge the public good—would seek to use it against us.”