Katz and Dogs: Fourth Amendment Detour to my Favorite Scalia Opinions

Advance Sentinel in a Helicopter

Original image by Jean-Marc Côté, Public Domain, via Wikimedia Commons and Public Domain Review. A pre-Katz perception of what twenty-first century surveillance could look like.

As soon as I learned that 2016’s cruel winter had taken from us not just David Bowie but also Justice Scalia, I wanted to write a tribute. Rainbow flag cake notwithstanding, the BFF of RBG wrote some of my all-time favorite opinions, protecting rights I hold dear and making me laugh. From this blog’s usual free speech and feminist fare, I detour to the Fourth Amendment.


Cat on phone

Public Domain image via Pixabay.


The Fourth Amendment protects “[t]he right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures . . ..” Historically, the reasonableness of a search was evaluated in terms of trespass. A warrantless search of an individual’s home or its curtilage could be unreasonable if it is a trespass—for example, entering a house without permission, breaking into a nearby shed, or sneaking into an office and stealing private documents.

The rise of modern surveillance technology, however, complicated things. Physical trespass onto another’s property was no longer necessary for the government to gather information—potentially incriminating information. This was true before e-mail (which could be hacked) or social media (which invites voluntary spilling of all kinds of details of one’s life) or smart phones (with cameras and microphones that could be remotely activated) were commonplace. The Supreme Court dealt with evolving technology and the Fourth Amendment decades ago, in its 1967 decision in Katz v. United States.

The events that led to the Katz decision are the following. Mr. Katz walked into a public phone booth in Los Angeles and placed some calls, one to Boston and one to Miami. Presumably, the door to the phone booth was closed. Presumably, Mr. Katz was not shouting into the phone. The conversations Mr. Katz had in that phone booth violated federal law; he was passing wagering information to his East Coast co-conversationalists. He did not see FBI agents poised with their ears pressed to the phone booth glass, because no such thing happened—not literally, anyway. What FBI agents had done was affix an electronic device to the outside of the phone booth that could both listen and record the sound taking place inside. That sound was Mr. Katz’s illegal information-sharing.

No trespass theory could classify this information-gathering as an “unreasonable search” under the Fourth Amendment. After all, the phone booth was public. Yet the conversation was private; Mr. Katz had every reason to think so. The Supreme Court, in an opinion written by Justice Stewart, held that an unreasonable search had occurred. The FBI’s activity had “violated the privacy upon which he justifiably relied.”

Justice Harlan wrote a separate concurring opinion containing the most memorable words of Katz v. United States: “reasonable expectation of privacy.” These words formed a new Fourth Amendment test.

Katz changed the theory of evaluating the reasonableness of searches for awhile, well into the years of e-mail, social media, and little computers in our pockets with microphones and cameras that could be remotely activated and even GPS technology that could track our every move.

United States v. Jones

In 2005, Antoine Jones parked his wife’s car in a public parking lot in Maryland. Over the next four weeks, he drove the car to and from locations that would connect him with drug trafficking. He didn’t see the FBI agents hanging onto his car, recording his every move; he didn’t see the FBI agents positioned along his route, tracking his travels; he didn’t see police officers waiting for him in every driveway or parking space, ready to follow him to his next location. That’s because they weren’t literally there, but metaphorically present with him on his errands, in the form of a GPS tracking device that the FBI had installed in the undercarriage of the car. The agents didn’t have a valid Maryland warrant authorizing this action.

Under Katz, no search had occurred. Mr. Jones’s “reasonable expectation of privacy” had not been violated. When Mr. Jones moved to suppress this evidence as having been the result of an illegal search, the trial court denied the motion. Traveling from place to place on public streets, the court reasoned, one has no reasonable expectation of privacy.

The Supreme Court disagreed. The 2012 opinion written by Justice Scalia relied upon an old theory to address new technology. He wrote:

The Government physically occupied private property for the purpose of obtaining information. We have no doubt that such a physical intrusion would have been considered a “search” within the meaning of the Fourth Amendment when it was adopted.

In other words, the placement of the GPS tracking device onto Mr. Jones’s wife’s car was a trespass, a physical occupation of his property, and therefore fell within the the pre-Katz understanding of the Fourth Amendment.

Jones didn’t overrule KatzJones showed that Katz doesn’t supplant the old trespass theory, but actually expands our rights under the Fourth Amendment. A search may occur when the government’s action 1) violates reasonable expectation of privacy or 2) is a physical occupation of private property.

Florida v. Jardines

Dog at door

A dog sitting outside a closed door. Lithograph after an etching by Huffam after A. Crowquill. via Wikimedia Commons. CC BY 4.0

A year later, Justice Scalia applied Jones in an opinion holding that bringing a trained police dog to the outside of Mr. Jardines’s home, in order to, without a warrant, determine what was inside the house, was a physical intrusion and, under the Fourth Amendment, a search. The police’s actions went beyond the polite custom, in Scalia’s words:

to approach the home by the front path, knock promptly, wait briefly to be received, and then (absent invitation to linger longer) leave. Complying with the terms of that traditional invitation does not require fine-grained legal knowledge; it is generally managed without incident by the Nation’s Girl Scouts and trick-or-treaters.

Describing the trained dog as a “device that is not in general public use,” Scalia’s opinion in Jardines shows how the Fourth Amendment’s boundaries could be tested as technology threatens to reduce our privacy more and more. Together, the Katz test and the Jonerevival of the trespass test can protect us more effectively than either test alone.


Posted in Fourth Amendment, Legal Analysis

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Constitutional law (mostly civil rights) for everyone! The author of this blog attempts to make legal issues, cases, and news stories with a consititutional connection accessible for any audience. The goal is to provide information, analysis, and an opportunity for conversation. Please feel free to ask questions or respond in the comments or via e-mail. Dialogue, disagreement, and most of all decorum are highly encouraged.
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Information on this blog is provided for educational purposes only and is not legal advice. Reading or interacting with this blog does not form an attorney-client relationship with the author. This blog should not be used as a substitute for competent legal advice from a licensed attorney.
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