Note | Constitutional Law
Applying the Exclusionary Rule to Carpenter Searches
by Kevin Ganley*

From Vol. 93, No. 3 (March 2020)
93 S. Cal. L. Rev. 571 (2020)

Keywords: Carpenter v. United States, the Fourth Amendment

This Note is useful in two respects. First and foremost, it provides a plausible approach for applying the exclusionary rule to mosaic searches, removing a thorny obstacle in the mosaic theory’s path. The after-act approach is also court friendly because it facilitates judicial review by incentivizing the government to show its work through sequencing its actions. Second and more subtly, this Note may encourage courts to avoid the mosaic theory altogether. The Supreme Court’s Fourth Amendment jurisprudence was already a “mess” before the digital age. This Note describes several complicated doctrinal puzzles that arise at the intersection of the exclusionary rule and the mosaic theory. Adopting the bright-line source rule would avoid having to address these difficulties.

Part I of this Note paints the backdrop underlying the Carpenter decision. It tracks the development of the Fourth Amendment search doctrine to the digital age and then demonstrates that over time the Court has adapted this doctrine in response to improvements in government surveillance technology. Then, Part I explains how the Court’s current analog-search rules, namely the third-party doctrine, have become outdated in the digital age.

Next, Part II of this Note explains how Carpenter marked a shift in the Court’s understanding of its Fourth Amendment search doctrine in the digital age but left open how to determine when exactly a Carpenter search occurs on new sets of facts. It will then more thoroughly introduce the mosaic theory and the source rule, which are two possible methods for determining when a Carpenter search occurs. In comparing the relative merits of each method, Part II will explain that, although the mosaic theory is theoretically sound, its application to the Court’s existing search doctrine presents many messy legal issues, including how to apply the exclusionary rule.

Part III addresses how to apply the exclusionary rule when a mosaic search occurs. In doing so, it briefly will introduce the exclusionary rule. It will then discuss the respective failings of the all-or-nothing and after-search approaches. Finally, Part III will outline the after-act approach and explain its various virtues, using the all-or-nothing and after-search approaches as foils.

*. Editor-in-Chief, Southern California Law Review, Volume 93; J.D. Candidate 2020, University of Southern California, Gould School of Law; B.B.A. Finance 2017, University of San Diego; B.A. Political Science 2017, University of San Diego. I would like to thank my Mom, my Dad, Matt, and Madeline for their love and support throughout my time in law school. I would also like to thank Professor Sam Erman for his guidance as I worked through the many versions of this Note as well Professor Orin Kerr for his feedback on my manuscript. Finally, I would like to thank the talented members of the Southern California Law Review for their excellent editing work.

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