REP in 4A Searches

What is the core Fourth Amendment question in the “reasonable expectation of privacy” (REP) analysis?

Whether government conduct intruded on a person’s reasonable expectation of privacy so as to constitute a “search” within the meaning of the Fourth Amendment.

If no REP, there is no “search,” and the 4A is not implicated.

What did the outline say about the historical shift in 4A analysis?

The Court originally focused on property/trespass and tangible items (pre-Katz), but after Katz (1967) the focus moved to privacy — what a person seeks to preserve as private may be constitutionally protected even without physical intrusion.

What is the Katz two-prong test for a reasonable expectation of privacy?

• Subjective prong: The person must have exhibited an actual, subjective expectation of privacy; and

• Objective prong: The expectation must be one society is prepared to recognize as reasonable.
  

• If either prong fails, there is no 4A “search.”

According to the outline, what factors help decide whether society recognizes an expectation of privacy as reasonable?

• The site/nature of the property or place examined

• The steps taken to keep it private

• The degree of government intrusion

• Whether the information was exposed to the public or a third party

• Whether the area is home/curtilage (more protection) vs. public/open field (less)

What approach did the Court use before Katz?

A property/trespass approach — if there was no physical intrusion into a person’s “persons, houses, papers, and effects,” then there was no search.

What did Olmstead v. United States (1928) hold under the pre-Katz approach?

Wiretapping a phone line was not a search because there was no physical intrusion into a constitutionally protected area and a conversation is not a tangible “effect.”

This is the classic trespass doctrine example and is no longer good law after Katz.

What did Katz v. United States (1967) change?

Katz replaced the pure property approach with a privacy approach. It held that “the 4th Amendment protects people, not places,” and that government surveillance can be a search even without physical trespass if it invades a reasonable expectation of privacy.

What is the classic Katz illustration from the outline?

A person using a public phone booth closed the door and thus manifested a subjective expectation of privacy; the Court said society is prepared to recognize that expectation as objectively reasonable, so the recording was a 4A search.

Name two categories where the outline said there is a reasonable expectation of privacy.

1. Curtilage of the home

2. Luggage/containers (Bond)
   In both, people typically manifest privacy efforts and society recognizes them.

Name several categories where the outline said there is no reasonable expectation of privacy.

• False friends / undercover informants (Hoffa; White)

• Open fields (Oliver; Hester)

• Trash left for pickup beyond curtilage (Greenwood)

• Information voluntarily given to third parties (Miller; Smith)

• Exterior of vehicles in public (Cardwell)

• Prison (Hudson v. Palmer)

What is “curtilage” according to the outline?

The area closely connected to the use of the home and within the intimate activities of the home — usually the area immediately surrounding and associated with the home. It typically carries a reasonable expectation of privacy.

What four factors from U.S. v. Dunn does the outline list to determine curtilage?

1. Proximity of the area to the home

2. Whether the area is within an enclosure surrounding the home

3. Nature of the uses to which the area is put

4. Steps taken by the resident to protect the area from observation

What did Florida v. Jardines (as described in the outline) say about bringing a drug dog to the front porch?

Bringing a drug-sniffing dog to the front porch (curtilage) to obtain information is a search and requires a warrant, because it’s an intrusion into a constitutionally protected area to gain information.

What did Collins v. Virginia (noted in the outline’s curtilage discussion) reinforce?

That curtilage + concealment (e.g., tarp over a motorcycle in the carport) = protected area. LEOs cannot move items to see what’s underneath without a warrant. It’s a search.

What did Bond v. United States hold about luggage?

A traveler’s luggage is an “effect” protected by the 4A, and physical manipulation/squeezing of the bag by police is a search because a reasonable traveler does not expect that level of tactile inspection.

What was the outline’s note about “administrative searches” like TSA?

Those are an exception — because the purpose is broad security, not individualized criminal investigation, probable cause is not required and travelers have a reduced REP in that context.

What is the general rule from the “false friends” cases in the outline?

There is no reasonable expectation of privacy in conversations voluntarily shared with another person, because you assume the risk that the person is an informant or will later reveal it to the government.

What did Hoffa v. United States (1967) hold?

When a person voluntarily speaks to another, he assumes the risk that the listener is not who he says he is or will later reveal the information to law enforcement — no 4A protection.

How did United States v. White (1971) extend Hoffa?

It said the rule does not change even if the “friend” is wearing a recording or transmitting device with government consent.

Still no REP — statutory wiretap rules don’t apply when one party consents.

What policy justification did the outline give for the false-friends rule?

Information gathered through undercover work is often essential to detect crime; the Court does not want to hinder undercover operations by recognizing an REP in voluntarily shared conversations.

What is the “general rule” of the Third-Party Doctrine from the outline?

There is no 4A REP in information voluntarily disclosed to a third party. Once you give info to a bank, phone company, or other intermediary, you lose control over it and assume the risk it will be conveyed to the government.

What did United States v. Miller say about bank records?

No REP in bank records because they are business records of the bank and the customer has voluntarily conveyed the information to a third party.

What did Smith v. Maryland (1979) say about phone numbers dialed?

• The caller knows the phone company gets the numbers, and

• By giving info to a 3rd party, he assumes the risk it will be shared.

Therefore, no REP.

What distinction did the outline make between content and non-content communications?

• Non-content (numbers dialed, to/from, envelope face) → easier for government to get; usually no REP.

• Content (letter contents, email body) → REP exists, so government usually needs a warrant.

What is the Open-Field Doctrine (Oliver; Hester) as described?

Entry into and exploration of an open field is not a search under the 4A, even if the field is fenced or posted “No Trespassing,” because an open field is not a house, paper, or effect, and people do not have a REP there.

What did the outline emphasize about “open fields”?

It does not have to be open or literally a field — it’s anything beyond the home and curtilage that is exposed to public view.

What was the holding in California v. Greenwood (1988) as your outline summarized it?

There is no REP in trash placed outside the curtilage and in a place accessible to the public (e.g., curb for pickup), because people assume the risk that animals, scavengers, or police can go through it. Police may search it without a warrant.

What counter-argument did the outline note for Greenwood, and how did the Court respond?

Defense argued people are forced to use municipal trash pickup and thus don’t voluntarily expose trash; the Court said that did not matter — placement at the curb is exposure to the public.

How did the outline treat postal mail and packages?

Contents of sealed first-class mail and packages (including via 3rd-party carriers) are protected — REP exists.

Exterior information (address, etc.) is not. By contrast, lower-class mail that may be opened by regulation does not support REP.

What did Cardwell v. Lewis (1974) represent in your outline?

That there is less REP in vehicles, especially exterior areas exposed to public view; a limited exterior inspection of a car in a public area does not violate a REP. Vehicles are “semi-public spaces.”

What did Hudson v. Palmer (1984) say about prison privacy?

No 4A REP in prison. Prisoners cannot reasonably expect a zone of privacy to hide prohibited items. Searches of prison cells do not implicate the 4A.

What is the general rule for aerial surveillance in the outline?

No search when government makes aerial observations from public navigable airspace in a nonintrusive manner that does not reveal intimate details of the home or curtilage.

What conditions did the outline list for aerial surveillance to be OK?

1. From public, navigable airspace

2. Physically nonintrusive

3. Does not reveal intimate activities associated with home/curtilage

If those are met —> No REP (no search)

Compare: Curtilage vs. Open Field.

• Curtilage: close to home; used for intimate home activities; often enclosed → REP → 4A applies.

• Open Field: beyond curtilage; even if fenced or posted → NO REP → 4A doesn’t apply.

Compare: Hoffa / White vs. Katz.

• Katz: protects communications when a person both shows an expectation of privacy and society accepts it.

• Hoffa/White: no REP in conversations voluntarily exposed to another person → you assume the risk.
  

So Katz doesn’t protect you from the person you chose to talk to.

Compare: Miller / Smith (3rd Party) vs. Mail contents.

• Miller/Smith: info voluntarily given to a company → no REP.

• Mail contents: not voluntarily exposed; sealed → REP → warrant needed.

Why does the outline say there is “no REP in things exposed to a third party”?

Because once information is shared, the individual assumes the risk that the third party will reveal it to the government; 4A does not protect misplaced confidence.

Is going through trash left on the curb a search?

No. Greenwood — no REP once trash is put out for collection beyond curtilage.

Is squeezing a bus passenger’s bag a search?

Yes. Bond — tactile manipulation exceeded what a passenger would expect.

Is listening to you through a wired informant a search?

No. White — no REP in what you tell another person; recording doesn’t change that.

Is flying over your yard at legal altitude and seeing marijuana plants a search?

No, so long as it’s from public airspace, nonintrusive, and doesn’t reveal intimate details.

Is entering the curtilage and moving a tarp to identify a vehicle a search?

Yes. Because it’s curtilage and the officer manipulated something to get information.

What is the rule for postal mail?

• Protected: Contents of sealed first-class mail and packages handled by postal or third-party delivery services.

• Unprotected: Fourth-class mail, which may be opened under federal regulations.

• Digital parallel: For emails, the subject line has no REP, but the message content does.

📝 Key idea: Protection follows the content, not the carrier.

What did Hudson v. Palmer (1984) hold about prison cells?

No Fourth Amendment REP in prison. Prisoners cannot reasonably expect privacy in their cells to hide or possess contraband. Searches of cells are not “searches” under the Fourth Amendment.

What is the general rule for aerial surveillance?

No search occurs when government observation is:

1. From public, navigable airspace,

2. Physically nonintrusive, and

3. Does not reveal intimate details of the home or curtilage.

What did California v. Ciraolo (1986) hold?

No REP in marijuana plants observed from a low-flying airplane over a fenced yard because anyone in public airspace could have seen the same thing.

📝 Failed the objective prong of Katz — society not prepared to protect that expectation.

What did Florida v. Riley (1989) add to aerial surveillance doctrine?

Observation from a helicopter in legal airspace is not a search so long as it doesn’t interfere with the target’s property and only uses naked-eye viewing or generally available technology.

What did Dow Chemical Co. v. United States (1986) hold?

Use of a powerful mapping camera to view an industrial complex from public airspace was not a search.

The property was commercial, not intimate like a home, so there was no reasonable expectation of privacy.

What did Kyllo v. United States (2001) decide about “through-the-wall” surveillance?

Using technology not in general public use (like a thermal imager) to explore details of the home that would previously have been unknowable without physical intrusion is a search. Police must get a warrant.

📝 Bright-line rule for advancing technology near the home.

What distinction does the outline make about tracking devices?

• Installation = potential seizure issue.

• Use/monitoring = potential search issue.
  Courts analyze both under the Katz REP framework

What was held in United States v. Knotts (1983)?

Using a beeper to track a vehicle’s movements on public roads was not a search. Since officers could have followed visually, there was no intrusion into a REP.

What did United States v. Karo (1984) add to Knotts?

Monitoring a beeper inside a private residence is a search, because it reveals information about the interior of the home that couldn’t have been obtained through ordinary observation.

📝 Rule: Tracking devices cannot be used to monitor persons or things inside the home.

What is the general rule about dog sniffs?

A well-trained dog’s sniff that detects only the presence or absence of contraband (a “binary search”) is not a search under the Fourth Amendment, so long as the officer is lawfully present where the sniff occurs.

What did United States v. Place (1983) hold?

A brief luggage sniff by a trained dog is not a search because:

1. It’s nonintrusive, and

2. It reveals only contraband, not private facts.

What did Illinois v. Caballes (2005) hold?

A dog sniff during a lawful traffic stop that reveals only the presence of contraband is not a search — as long as the sniff does not prolong the stop beyond its ordinary duration.

What limitation did Florida v. Jardines (2013) add?

Bringing a drug dog to the front porch (curtilage) of a home is a search and requires a warrant.
📝 The Court relied on property-based reasoning — physical intrusion into a constitutionally protected area to gather information.

What principle connects Kyllo and Jardines?

Both reinforce that the home and its curtilage receive the highest 4A protection, and using sense-enhancing tools (technology or trained animals) to gather information from that zone without a warrant constitutes a search.

Summarize which “third-party/tech” contexts have and lack a reasonable expectation of privacy.

Context	REP?	Leading Case
Sealed first-class mail	✅ Yes	Ex parte Jackson (implied), outline p. 233
Fourth-class mail	❌ No	Postal regs allow opening
Prison cells	❌ No	Hudson v. Palmer
Aerial surveillance (public airspace)	❌ No	Ciraolo, Riley, Dow Chemical
Through-wall thermal scan	✅ Yes	Kyllo
Tracking on public roads	❌ No	Knotts
Tracking inside home	✅ Yes	Karo
Dog sniff in public area	❌ No	Place, Caballes
Dog sniff at curtilage	✅ Yes	Jardines

How did Florida v. Riley (1989) refine Ciraolo?

Viewing inside a greenhouse from a helicopter hovering at 400 feet was also not a search since the craft was within legal navigable airspace and the observation did not disturb the property or expose intimate home details.

What principle emerges from Ciraolo, Riley, and Dow Chemical (1986)?

Observation from lawful public vantage points using commonly available technology is not a search;

Privacy expectations are diminished for outdoor or industrial areas.

However, the home and curtilage remain highly protected zones.

What happened in United States v. Jones (2012)?

Attaching a GPS tracker to a vehicle and monitoring its movements constitutes a search because it involves physical trespass on private property for the purpose of obtaining information.

📝 The majority relied on property-based reasoning, while concurring opinions noted long-term monitoring also violates a reasonable expectation of privacy.

How did Jones relate to earlier beeper cases (Knotts, Karo)?

Jones combined both trespass and privacy concepts—clarifying that technology use involving physical attachment (as in GPS) revives the property-intrusion test, even post-Katz.

• Knotts: monitoring on public roads = no search.

• Karo: monitoring inside home = search.

• Jones: attaching device itself = search.

What did Carpenter v. United States (2018) hold?

Government access to historical cell-site location information (CSLI) is a search requiring a warrant. Individuals maintain a reasonable expectation of privacy in the record of their physical movements, even though held by a third party.

How does Carpenter limit the traditional Third-Party Doctrine?

It carved out an exception: “voluntary exposure” does not apply to automatic, comprehensive digital data (like CSLI). Continuous, long-term tracking by technology implicates privacy even if the info is stored by a third party.

How do Kyllo and Jardines together shape the “sense-enhancement” rule?

Both hold that the use of tools or devices (tech or dogs) not generally available to the public, to obtain information about the interior of a home or its curtilage, constitutes a search requiring a warrant.

What analytical tests now govern technological surveillance under the Fourth Amendment?

1. Physical trespass test (Jones): If the government physically intrudes into a constitutionally protected area to obtain info, it’s a search.

2. Katz privacy test: Even without trespass, if government activity violates a reasonable expectation of privacy, it’s a search.

3. Carpenter digital-data principle: Long-term, automatic data collection can trigger 4A protection even if information is held by a third party.

How do courts weigh “common use” technology?

If the device or method is in general public use (e.g., binoculars, standard cameras), its use is usually not a search. But if the technology is specialized or invasive (thermal imager, advanced GPS, high-power sensors), courts deem it a search when directed at the home.

What remains the “core” of Fourth Amendment protection after Jones, Carpenter, and Kyllo?

The home and curtilage. These spaces maintain maximum constitutional protection, and any government intrusion—physical or technological—without a warrant is presumptively unreasonable.