Introduction

Carpenter v. United States, 138 S. Ct. 2206 (2018), is a landmark decision by the United States Supreme Court that significantly expanded Fourth Amendment protections in the digital age. The case centered on whether the Government's acquisition of historical cell-site location information (CSLI) constitutes a search under the Fourth Amendment, thereby requiring a warrant supported by probable cause.

Timothy Ivory Carpenter, the petitioner, was convicted of robbery and firearm charges based in part on extensive cell-site location data that placed his phone near the scenes of the crimes. Carpenter argued that obtaining his historical CSLI without a warrant violated his Fourth Amendment rights.

Summary of the Judgment

The Supreme Court, in a majority opinion delivered by Chief Justice Roberts, held that accessing historical CSLI without a warrant does indeed constitute a search under the Fourth Amendment. The Court reversed the Sixth Circuit's decision, which had relied on the third-party doctrine established in SMITH v. MARYLAND and UNITED STATES v. MILLER, concluding that individuals do not have a reasonable expectation of privacy in information they voluntarily share with third parties.

However, the Court in Carpenter declined to extend the third-party doctrine to the realm of CSLI due to the pervasive and comprehensive nature of the data, which can reveal intimate details of an individual's life over extended periods. Consequently, the Government must obtain a warrant supported by probable cause to access historical CSLI.

The decision was accompanied by dissenting opinions from Justices Kennedy, Thomas, and Gorsuch, who argued for maintaining the third-party doctrine and expressed concerns about hindering law enforcement capabilities.

Analysis

Precedents Cited

The majority opinion in Carpenter extensively discussed precedents such as:

• SMITH v. MARYLAND (442 U.S. 735, 1979): Established the third-party doctrine, stating that individuals have no reasonable expectation of privacy in information voluntarily shared with third parties.
• UNITED STATES v. MILLER (425 U.S. 435, 1976): Similar to Smith, it held that bank records are business records and not protected under the Fourth Amendment when subpoenas are served.
• KATZ v. UNITED STATES (389 U.S. 347, 1967): Introduced the "reasonable expectation of privacy" test, moving beyond property-based concepts to protect individual privacy.
• Jones v. United States (565 U.S. 400, 2012): Highlighted technological advancements in surveillance, reinforcing that new technologies require fresh Fourth Amendment considerations.
• KYLLO v. UNITED STATES (533 U.S. 27, 2001): Demonstrated that using technology not in general public use to enhance government's insight into details of a private home constitutes a search.

Legal Reasoning

The Court recognized that while past decisions allowed the Government to access certain types of records held by third parties without a warrant, the nature of modern CSLI differs fundamentally. CSLI provides a detailed and comprehensive chronicle of an individual's movements, akin to continuous GPS tracking, but stored by a third party (the wireless carrier).

The majority found that extending the third-party doctrine to CSLI would allow the Government unobstructed access to vast amounts of personal data without individualized suspicion, undermining the Fourth Amendment's protections.

Key considerations included:

• The granularity and comprehensiveness of CSLI compared to previous third-party records.
• The ease and low cost with which the Government can obtain CSLI en masse.
• The retrospective nature of CSLI data, allowing analysis of an individual's movements over extended periods.

Therefore, the Court held that individuals have a legitimate expectation of privacy in their CSLI, and the Government must obtain a warrant supported by probable cause to access this information.

Impact

The decision in Carpenter has profound implications for privacy rights in the digital era:

• Strengthens Fourth Amendment protections against invasive digital surveillance.
• Requires law enforcement to obtain warrants for accessing historical CSLI, aligning digital data access with traditional privacy expectations.
• Sets a precedent for evaluating other types of digital data, potentially influencing future rulings on privacy in the age of Big Data.
• Challenges existing law enforcement practices, necessitating adjustments in investigative procedures to comply with the warrant requirement.

Complex Concepts Simplified

Fourth Amendment

The Fourth Amendment protects individuals against "unreasonable searches and seizures" by the Government, ensuring privacy and security of persons, houses, papers, and effects.

Search and Seizure

A "search" occurs when the Government intrusively obtains information that an individual has a reasonable expectation of privacy in. A "seizure" involves the taking of someone's property.

Third-Party Doctrine

Established in SMITH v. MARYLAND and UNITED STATES v. MILLER, it posits that individuals lose their Fourth Amendment protections over information voluntarily shared with third parties, such as phone companies or banks.

Reasonable Expectation of Privacy

Originating from KATZ v. UNITED STATES, it's a test to determine whether an individual legally enjoys protection under the Fourth Amendment in a given situation.

Cell-Site Location Information (CSLI)

CSLI refers to data that records the location of a cell phone at various times, created each time the phone connects to a cell site. It can precisely track an individual's movements over extended periods.

Conclusion

Carpenter v. United States marks a pivotal shift in Fourth Amendment jurisprudence, adapting constitutional protections to the challenges posed by modern technology. By ruling that historical CSLI constitutes a search, the Supreme Court acknowledged the invasive potential of digital data collection and underscored the necessity for law enforcement to seek judicial oversight through warrants.

This decision not only reinforces individual privacy rights in the digital age but also sets the stage for future legal battles over data privacy and government surveillance. As technology continues to evolve, Carpenter provides a foundational precedent ensuring that constitutional protections keep pace with innovation, balancing the needs of law enforcement with the fundamental rights of individuals.