What counts as a search

The Privacy Baseline: Two Routes to a Search

A Fourth Amendment search occurs when government conduct invades a reasonable expectation of privacy or uses a protected-property trespass to obtain information. The first route is the Katz test: the person must actually expect privacy, and society must recognize that expectation as reasonable. Both requirements matter. A secret hope of privacy in something knowingly exposed to the public is not enough; conversely, the fact that conduct occurs outside a home does not automatically eliminate privacy.

Ask what information the government obtained, how it obtained it, and from what place, person, paper, or effect. Naked-eye observation from a lawful public vantage generally reveals only what the person exposed. Ownership is relevant but not decisive. A home, hotel room, or overnight guest’s private space ordinarily supports privacy; a brief commercial visitor’s activities in another person’s apartment ordinarily do not. The question is the social and physical setting, not simply who holds title.

There is also a separate Jones property-based test. A search occurs when the government physically trespasses on a person, house, paper, or effect in order to obtain information. That route does not require proving a reasonable expectation of privacy. Thus, attaching a tracking device to a vehicle to monitor its movements is a search even if the vehicle travels on public roads. The two routes are alternatives, not cumulative requirements.

Run the classification in this order:

1. Ask whether the government committed a protected-property trespass to obtain information. If yes, the conduct is a search under the Jones property-based test.

2. If not, apply Katz: did the person actually expect privacy, and is that expectation objectively reasonable?

3. If neither route applies, the conduct is not a Fourth Amendment search, although a different constitutional issue-such as a seizure-may still exist.

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The most important near miss is what is observed versus how it is obtained. Seeing a person from a public sidewalk may be permissible observation; physically entering protected curtilage to obtain the same information may be a search. Likewise, voluntarily telling a person something differs from a government officer secretly listening from outside the conversation.

This chapter is closed-book: commit the two Katz requirements, the Jones alternative, and the location-and-technology distinctions to memory.

Fields Around the Home: Open Ground, Curtilage, and Surveillance

The open-fields doctrine holds that an individual has no Fourth Amendment reasonable expectation of privacy in an open field, even when the field is privately owned, fenced, marked “No Trespassing,” or not visible from a public road. Officers may enter and observe an open field without creating a Fourth Amendment search. The doctrine protects the land classification, not every object located there. A vehicle or other effect in an open field may still receive separate protection under the Jones property-based test.

Curtilage is the area immediately surrounding and associated with the home. It receives the home’s Fourth Amendment protection because it is closely tied to domestic life. A detached structure, backyard, porch, or enclosed area may be curtilage; distance alone does not decide the issue.

The Dunn curtilage factors are:

1. The area’s proximity to the home.
2. Whether the area is within an enclosure surrounding the home.
3. The nature of the uses to which the area is put.
4. The steps taken by the resident to protect the area from observation by people passing by.

No single factor is conclusive. A barn far from the house, outside the home’s enclosure, used for non-domestic activity, and not protected from observation is more likely an open field. A small patio immediately behind the house, inside the home’s fence, used for family activities, and shielded from public view is more likely curtilage.

The next distinction is lawful vantage point versus physical intrusion. Police may observe a home or backyard from a place where members of the public may lawfully stand. In California v. Ciraolo and Florida v. Riley, aerial observation from lawful navigable airspace did not create a search merely because officers saw a fenced backyard. Similarly, ordinary binocular observation from a lawful vantage generally does not create a search. But a public vantage point does not authorize officers to climb a fence, enter a protected patio, or place equipment inside curtilage.

Technology changes the analysis when it reveals information that ordinary observers could not obtain. Under Kyllo, using sense-enhancing technology that is not in general public use to obtain information about the interior of a home that could not otherwise be obtained without physical intrusion is a search. The rule is narrow: it concerns the home’s interior and technology unavailable to the general public. It does not make every camera, flashlight, binocular, or aerial observation a search.

The Jones property route covers a different technology problem. Physically attaching a GPS device to a vehicle to obtain information is a search because the government trespasses on an effect. Long-term, comprehensive monitoring may also implicate Katz even when each individual movement occurs in public. Do not reason that public visibility of every trip automatically defeats privacy in a detailed, aggregated record.

Historical cell-site location information illustrates the modern third-party near miss. Under Carpenter, obtaining at least seven days of historical CSLI from a wireless carrier is a search despite the carrier’s possession of the records. The data creates a detailed, comprehensive record of a person’s movements that is generated automatically rather than deliberately disclosed in a single transaction. Carpenter is a specific holding about historical CSLI, not a general abandonment of the ordinary third-party doctrine.

Once the conduct is classified as a search, the warrant and warrantless-exception chapters determine whether it was constitutionally authorized. This chapter’s question ends with the search classification.

False Friends and Dog Noses: Voluntary Disclosure Versus Curtilage Intrusion

A false friend is a person whom the target admits into a private conversation or place but who is secretly cooperating with the government. The target has no reasonable expectation that the invited participant will keep the information confidential. Under the false-friend or assumption-of-risk doctrine, the government generally commits no search when:

• an informant hears the target’s statements and later reports them;
• an undercover officer records or transmits a conversation with the target; or
• an undercover officer enters by invitation and observes what the invitation permits.

The rule applies because the target voluntarily exposed the information to another participant. It does not depend on whether the target subjectively hoped the participant was loyal. Hoffa, United States v. White, and Lewis illustrate the distinction.

The near miss is an outsider’s surveillance. If no participant shares the information and officers secretly use a device to overhear a conversation from outside the protected place, the false-friend doctrine does not apply. That conduct is tested under Katz. Nor does an invitation to enter authorize a government agent to conduct a broader physical search unrelated to the invited activity. The officer may use what the participant was invited to see or hear; the invitation is not an unlimited license to rummage.

The ordinary dog sniff distinction is similarly narrow. In United States v. Place, a trained dog’s sniff of luggage in a public setting was not a search because the sniff disclosed only the presence or absence of contraband, in which there is no legitimate privacy interest. In Illinois v. Caballes, a dog sniff of the exterior of a vehicle during a lawful traffic stop likewise was not a search on the stated facts. The dog sniff did not expose lawful private details; it revealed only whether contraband was present.

The decisive change is location and physical intrusion. In Florida v. Jardines, officers brought a drug-detection dog onto the home’s front porch to investigate the home. The porch was curtilage, and the officers physically entered it to gather information. The dog sniff was therefore a search. The fact that the dog could reveal only contraband did not erase the curtilage intrusion.

Thus, compare these four situations:

• Dog sniff of luggage in a public place: ordinarily no search under Place.
• Dog sniff of a vehicle’s exterior during a lawful traffic stop: ordinarily no search under Caballes.
• Dog sniff in an open field: ordinarily no search because open fields carry no Fourth Amendment privacy protection.
• Dog sniff conducted by entering a home’s porch or other curtilage: search under Jardines.

The following item combines the two most easily confused rules.

Lee invited an undercover officer into his home to discuss a proposed drug sale. Without Lee’s knowledge, the officer recorded the conversation. Later that evening, other officers walked onto Lee’s front porch with a trained dog, and the dog sniffed the closed front door.

Recurring errors to eliminate:

• Treating a “No Trespassing” sign as conclusive when the area is still an open field under the Dunn factors.
• Treating every fenced area as curtilage without asking how close it is to the home and how it is used.
• Forgetting that a public view can become a search when officers physically intrude into curtilage or use Kyllo-type technology.
• Applying the false-friend doctrine to an officer who secretly listens without participating in the conversation.
• Saying every dog sniff is permissible when Jardines makes a porch or other curtilage sniff a search.

Three Final Runs: Facts That Separate the Doctrines

High-Yield Points - ⚡ Biggest Takeaways

Apply Katz’s actual-expectation and social-reasonableness requirements, but test Jones’s property-trespass route separately. Open fields lose Fourth Amendment protection; curtilage keeps it under the Dunn factors. A false friend may record what was voluntarily shared, but a dog sniff on home curtilage is a Jardines search.