Criminal Procedure (Fourth Amendment)

Carpenter v. United States — Study Notes

585 U.S. ___, 138 S. Ct. 2206, 201 L. Ed. 2d 507 (2018) (U.S. Supreme Court)

Study notes for Carpenter v. United States: professor notes, cold call prep, exam angles, and memory aids.

Historical cell-site location information is protected under the Fourth Amendment and requires a warrant supported by probable cause.
Professor Notes

In Carpenter v. United States, the Supreme Court addressed the intersection of modern technology and the Fourth Amendment's protection against unreasonable searches. The Court emphasized that obtaining historical cell-site location information (CSLI) constitutes a search under the Fourth Amendment, requiring a warrant supported by probable cause. This ruling is pivotal as it underscores the importance of safeguarding personal privacy in an era where technology tracks our movements critically. The decision also reflects the Court's recognition that the accumulation of data over time reveals sensitive personal information, which must be protected under constitutional standards.

Professors may highlight the dissenting opinions as well, illustrating the legal and cultural divide on how technological advancements challenge existing legal frameworks. It is crucial for students to understand not just the majority opinion but also the implications of the dissent in future cases concerning digital privacy and the Fourth Amendment.

Cold Call Prep
  1. 1What was the primary legal issue in Carpenter v. United States?
  2. 2How did the Court's ruling on CSLI impact Fourth Amendment jurisprudence?
  3. 3What are the implications of viewing cell location data as a search?
  4. 4Can you explain the difference between a warrant supported by probable cause and an SCA § 2703(d) order?
  5. 5What are potential exceptions to the warrant requirement under the Fourth Amendment?
  6. 6How might states respond to this decision regarding police use of technology?
  7. 7In what ways could Carpenter's reasoning extend to other forms of digital data?
Mnemonic Device

CELL: Cell data is a Search under the Fourth.

Distinguish From
CaseDistinction
United States v. JonesIn Jones, the Court held that using a GPS device placed on a vehicle constituted a search, reinforcing the notion that physical intrusion is also a search, while Carpenter focuses on digital data without physical trespass.
Smith v. MarylandSmith established the third-party doctrine, which permitted warrantless acquisition of phone numbers dialed from a landline, differing from Carpenter by emphasizing user consent given to providers, which does not apply to historical CSLI.
Policy Arguments

For the Rule

Requiring a warrant for CSLI protects individual privacy rights in an age of pervasive surveillance and helps restrain government overreach.

Against the Rule

Imposing a warrant requirement could hinder law enforcement's ability to effectively investigate crimes and diminish public safety.

Class Discussion Points
  • The balance between technological advancement and privacy rights.
  • How Carpenter v. United States may influence future cases related to digital privacy.
  • Reflections on the implications of the ruling for law enforcement practices and data collection.
  • Potential state legislations arising in response to the ruling.
  • Comparative analysis of privacy protections under the Fourth Amendment in the digital age.
Exam Angle

Carpenter v. United States often appears on exams in discussions surrounding the Fourth Amendment and digital privacy. Students should be prepared to analyze the decision's implications for warrant requirements and the evolving interpretation of 'search' in the context of technology.

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