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The Third-Party Doctrine and the Fourth Amendment

Posted by Dmitry Gorin | Dec 08, 2023

The Fourth Amendment to the United States Constitution is a critical protection for citizens, safeguarding them from unreasonable searches and seizures. However, this protection is not absolute. 

The third-party doctrine, a legal principle developed through court decisions, provides an exception to this rule based on the notion that citizens don't have a reasonable expectation of privacy for information they have made public. 

Third-Party Doctrine and the Fourth Amendment
The third-party doctrine says there is no reasonable expectation of privacy for info made public.

In the digital age, the third-party doctrine may have profound implications for our privacy, thanks partly to technologies that consistently track our behaviors.

Under the Fourth Amendment, the home is a castle where someone may retreat and “be free from unreasonable governmental intrusion.” It is afforded the highest level of protection. However, suppose a home is enhanced by artificial intelligence.

In that case, there is no reasonable expectation of privacy in data shared with third parties, such as Amazon. In other words, the third-party doctrine says there is no expectation of privacy in information voluntarily provided to others. 

As noted, the Fourth Amendment protects the right to be secure in one's person, house, papers, and effects against unreasonable searches and seizures. Recently, the Amendment has taken on a new meaning. 

We mail our DNA to discover our family history in our modern society. We depend on Alexa microphones in our homes to make life easier. We store documents in Cloud and Dropbox. Voluntary exposure is at the core of the third-party doctrine, but technology has changed privacy protections. Let's review this topic in more detail below.

Overview of the Fourth Amendment

The Fourth Amendment protects U.S. inhabitants from illegal searches and seizures of their “houses, papers, and effects.” This means law enforcement and federal investigators must obtain a warrant based on “probable cause” to conduct a search. Probable cause refers to a reasonable belief, based on factual evidence, that a crime has been committed. 

The purpose of the Fourth Amendment is to ensure that citizens have an expectation of privacy and can live free from the fear of arbitrary or unjustified intrusions by the government.

Under the United States Constitution, the Fourth Amendment says, “The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched and the persons or things to be seized.”

The Third-Party Doctrine: An Evolving Exception to the Fourth Amendment

Over time, court decisions have carved out exceptions to the Fourth Amendment. One of these has come to be known as the third-party doctrine. 

This doctrine holds that individuals lose their expectation of privacy when they voluntarily provide information to a third party. This means that in many cases, law enforcement can obtain information you've shared with others without needing a warrant.

The Third-Party Doctrine
There has been many court decisions have carved out exceptions to the Fourth Amendment.

Katz v. United States (1967), decided by the Supreme Court in 1967, significantly reshaped our understanding of the Fourth Amendment's protections against unreasonable searches and seizures. 

The case centered around Charles Katz, who was charged with transmitting wagering information by telephone across state lines. Katz used a public phone booth for his illicit activities, and unbeknownst to him, the FBI had attached an electronic eavesdropping device outside the booth to record his conversations. 

The Supreme Court ruled that the government's actions violated the Fourth Amendment, holding that even in a public phone booth, Katz had a “reasonable expectation of privacy” and that the government's warrantless eavesdropping constituted an illegal search. 

However, the Court decision also included the following statement: “What a person knowingly exposes to the public, even in his own home or office, is not a subject of Fourth Amendment protection.”  This statement set the stage for what would emerge as the third-party doctrine in subsequent court cases—namely, United States v. Miller (1976) and Smith v. Maryland (1979). 

In Miller, the Court ruled that the Fourth Amendment did not protect bank records because the information was voluntarily shared with a third party, the bank. Smith extended this logic to telephone numbers dialed, holding that the caller had no reasonable expectation of privacy because the information was voluntarily conveyed to the telephone company.

The Digital Age: New Challenges and Controversies

The advent of digital technologies and the internet has amplified the reach of the third-party doctrine. Today, we share vast amounts of data with third parties—from our search queries on Google to our location data on smartphones. 

The Digital Age and Third-Party Doctrine
New digital technologies and the internet have expanded the reach of the third-party doctrine.

One prominent example is Amazon's Alexa, a virtual assistant that responds to voice commands and forms the central hub for many “smart homes.”

 Alexa “listens” for a “wake word” to process commands but records every interaction after the wake word is spoken. This raises significant privacy concerns and has sparked much debate on whether law enforcement can access your Alexa data without a warrant under the third-party doctrine.

Recent court decisions seem to be trending toward limiting the reach of the third-party doctrine—mainly on the premise that the voluntary exposure of personal information is becoming a thing of the past and that divulging such data is no longer a meaningful choice. 

Carpenter v. United States, a 2018 Supreme Court case, marked a significant shift in the interpretation of the third-party doctrine in the context of modern technology. 
The case revolved around Timothy Carpenter, whose cell-site location information was obtained by the FBI without a warrant, leading to his conviction for robbery

The Supreme Court ruled that acquiring such records is a search under the Fourth Amendment, requiring a warrant supported by probable cause. The ruling recognized the digital age's unique privacy concerns, particularly the pervasive nature of long-term location tracking and the inevitability of individuals leaving digital footprints.

Protecting Your Privacy and Your Rights

The third-party doctrine originated from the idea that the law does not protect anyone who relays information to a trusted accomplice who later betrays them.  

The Court has declined to extend the third-party doctrine to data gathered by cell phones by recognizing their immense storage capacity and necessity to modern life. 

Due to this necessity, the Court deemed the rationale behind the doctrine, the voluntary assumption of risk, inapplicable in that context.

Understanding these legal principles is critical for anyone accused of a crime. If you believe the evidence against you was obtained through a warrantless search, understanding the Fourth Amendment and the third-party doctrine can help you challenge its admissibility in court. 

A skilled criminal defense attorney can evaluate your situation and determine how to protect your Fourth Amendment rights. You can contact our law firm for a case review by phone or via the contact form. Eisner Gorin LLP is based in Los Angeles, California.

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About the Author

Dmitry Gorin

Dmitry Gorin is a licensed attorney, who has been involved in criminal trial work and pretrial litigation since 1994. Before becoming partner in Eisner Gorin LLP, Mr. Gorin was a Senior Deputy District Attorney in Los Angeles Courts for more than ten years. As a criminal tri...

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