The Champion: Building on Carpenter: Six New Fourth Amendment Challenges Every Defense Lawyer Should Consider by Michael Price and Bill Wolf (NACDL, Dec. 2018) at 20-25:
The implications of the Supreme Court’s decision in Carpenter v. United States are just now coming into view as lower courts begin to apply Carpenter’s lessons to other forms of modern surveillance. In Carpenter, the Court held that a warrant is required to access more than six days of historical “cell site location information” — data obtained from the cellphone service provider indicating where a phone is connected to the cellular network. But the Court’s reasoning was not so limited. Instead, Carpenter marked another milestone in the Court’s process of rethinking Fourth Amendment doctrines in the digital age. This article offers a snapshot of some current investigative techniques that may be ripe for constitutional challenges in a post-Carpenter world.
Picturing the Post-Carpenter Landscape
Broadly speaking, two kinds of cases will be most directly affected by the Carpenter ruling: “location tracking” cases and “third-party records” cases. As Carpenter was quick to acknowledge, “personal location information maintained by a third party … does not fit neatly under existing precedents.” Instead, it implicates two, previously distinct strands of Fourth Amendment law: (1) the “public space” doctrine, which concerns the privacy of one’s physical location and movements; and (2) the “third-party” doctrine, which governs the privacy of things people share with others. Accordingly, this article first examines three new location tracking technologies through a post-Carpenter lens, and then addresses government access to other kinds of data maintained by third parties.