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The missing “subjective expectation of privacy” test

In a forthcoming article, “Katz Has Only One Step: The Irrelevance of Subjective Expectations,” I argue that the subjective prong of Katz v. United States, used to identify a Fourth Amendment “search,” is a phantom doctrine. The Supreme Court recites the test, but it doesn’t make a difference. Establishing a search under Katz requires only one step, not two: the objective test is all that matters.

This is one of two posts explaining the article. Today, I’ll address the empirical part of the paper. Tomorrow, I’ll cover the historical explanation for how we got here.

The paper tries to understand how courts apply the Katz test by examining every case applying Katz that was handed down in 2012. 540 such cases were identified and analyzed. The results suggest that the subjective part of Katz makes no difference to any actual cases.

Recall that, in theory, Katz requires a defendant to prove both a subjective and an objective expectation of privacy before a court will hold that a search occurred. With that in mind, consider these results:

  • Only 43% of the cases applying Katz even mentioned the subjective test.
  • In the 103 cases that held a search had occurred, 86 cases (83%) applied the objective test and announced that a search occurred without even considering whether a subjective expectation of privacy had been established.
  • Zero cases held that there was an objective expectation of privacy but no subjective expectation of privacy. These are the cases in which the subjective test clearly would be outcome-determinative. No such cases were found.
  • Ten cases applied the subjective expectation of privacy test and reached an outcome without also applying the objective test. However, a review of these ten cases show that they either were cases that mistakenly applied the objective test and mislabeled it the subjective test or else would have reached the same result under the objective prong had it been reached.

Among the 540 cases in the data set, I couldn’t find a single case in which the subjective test appeared to alter outcomes. The majority of cases didn’t mention the subjective test, and courts usually didn’t bother to apply it even when the “two step” test should have required it. On paper, Katz is two steps. But in practice, it seems that Katz is only one step: Whether government conduct is a search hinges only on the objective prong.

The obvious question is, why would the Supreme Court adopt the subjective test if it makes no difference to outcomes? I’ll answer that in my next post.

Orin Kerr is the Fred C. Stevenson Research Professor at The George Washington University Law School, where he has taught since 2001. He teaches and writes in the area of criminal procedure and computer crime law.

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