Put simply, a seize is when an officer restricts the movements of an individual and a search is to intrude on the privacy of the individual to obtain information.

The Fourth Amendment protects against unreasonable searches and seizures without a warrant. However, with the passage of time and development of technology, important ways of understand a search and seizure has become relevant. The purpose of this article is to give an overview of how those definitions have developed.


Katz v. United States

389 U.S. 347 (1967).

Katz was convicted of communicating wagering information by telephone. He appealed.


Was the evidence obtained by wiretapping an unlawful search in violation of the Fourth Amendment?


The Fourth Amendment protects people, not places. If a person exposes information in the public, that information is subject to a search. If the person expects privacy, then the information is not subject to a search.


The evidence here was obtained illegally. Reversed.


Katz was convicted of communicated wagering information by telephone. The evidence for his conviction came because the FBI was listening in on his phone calls via wiretapping, which were made from within a public telephone box. Katz would enter the box, close the door, and then make the phone call.

The officers made sure that they limited their surveillance only to Katz and only to the calls they were sure was illegal. Additionally, they did not enter the telephone box. However, they had no warrant (judicial authority) to conduct the search.


Previously, the Fourth Amendment was interpreted to only protect an individual within a certain location and penetration of that location. Olmstead, 277 U.S. 438 (1928). That is why the government and Katz arguments mostly focused on whether the phone booth was public or private.

Here, however, the Court emphasizes that at the Amendment protects people, not places. As such, if the person expects privacy when the enter into an area, then they should be afforded that privacy. The fact that the officers limited their actions has no bearing on this case because those were exercises of self-restraint, not judicial-restraint.

The concurrence establishes the reasonable expectation of privacy. This test is what is utilized today.

Alternatively, the dissent focuses on how the language of the Constitution protects places, and this case is an example of the Court reading text into the Constitution. Nothing in the Constitution protects against eavesdropping (a practice that existed at the founding), and wiretapping is a modern version of eavesdropping.

Additional Notes

The reasonable expectation of privacy test has both a subjective and objective component. The targeted individual of the search must expect privacy (subjective), and that expectation must be deemed reasonable by society (objective).

United States v. Jones

565 U.S. 400 (2012).

Jones was convicted of dealing drugs. He appeals.


Was the evidence gathered by the GPS attached to Jones’ car an illegal search in violation of the Fourth Amendment?


An unreasonable search not only applies to people, but applies to places.


This was an unreasonable search. The evidence is dismissed and Jones is entitled to a new trial.


Jones was a club owner and suspected of dealing in drugs. A warrant was obtained to attach a GPS to the bottom of his Jeep within 10 days. On the 11th day, the GPS was installed and tracked Jones’ movements for four weeks. At one point the battery had to be changed. The data collected produced several hundred entries of data which was ultimately utilized in helping obtain a conviction (despite the defendant’s objections that the evidence be removed).


The Fourth Amendment protects people and places. If this action was committed in the 1800s, this would have been considered a trespass. For these reasons, secretly attaching a GPS would be unreasonable.

The concurrence however thinks that the Katz concurrence test should be applied. That is, what is the respondant’s reasonable expectation of privacy? The conclusion is the same, but it still allows for short-term searches or potentially long-term searches for intense crimes.

Additional Notes

This case sets forth the trespass test. Did the search physically intrude on the target’s protected interests (person, house, etc.) with the intent to obtain information.

State v. Bobic

996 P.2d 610 (Wash. 2000).

Bobic had several stolen car parts in a storage locker. The officers saw these parts in a hole in the wall. From these observations, they obtain a warrant, recover the goods, and charge Bobic with a crime.

Using Katz, the expectation of privacy test, this is not a search because the hole in the wall. Although he may expect privacy, this exception is unreasonable because observations could be made through the hole.

Under Jones, the trespass test, this is not a search. Nothing goes through the peep-hole, viewing occurred from an open area, etc.

This principle is called the plain view doctrine (also applies to smell and hearing). This can be used as a defense against an accusation that a search occurred. If the object is in plain view (use of senses without extraordinary means), observed from a place where the officer’s have a right to be, then the observations does not constitute a search. The plain view doctrine also applies to flyovers and garbage that is left to be collected (must be on the curb).

Bond v. United States

529 U.S. 334 (2000).

Bond was a passenger on a bus. The bus was stopped, border control boarded and checked passenger identification and luggage. The officer touched Bond’s bag, felt a brick like substance, obtained permission to look in the bag, and discovered illegal drugs. Was the initial touch a search?

Under Katz, this is a search because this was extraordinary manipulation of the bag. Touching a bag on a bus is normal, but too much equaled

Under Jones, this is a search because touching a bag is an extraordinary manner is trespass.


A seizure is when the officer interferes with an individual’s possessory interest in some property. Typically, this occurs in restricting the movement of an individual. A seizure typically takes one of three levels:

  1. A consensual conversation – no need to justify stopping to chat with the individual.
  2. Stop – must have “reasonable suspicion” also defined as “individualized or articulable suspicion.”
  3. An arrest – must have “probable cause.”

Most interactions involve consensual conversations or stops. The tricky part is knowing when one method of seizure turns into another.

United States v. Mendenhall

446 U.S. 544 (1980).

Mendenhall was convicted of transporting illegal narcotics. She appealed.


Was the interaction the agents had with Mendenhall an illegal seizure (improper stop) during the first interaction.


A person has been seized within the meaning of the Fourth Amendment only if, in view of all the circumstances surrounding the incident, a reasonable person would have believed that he was not free to leave.


Here, the facts do not show that there was a seizure.


Mendenhall exited a flight and was acting in a suspicious manner that caused a few agents to approach her, identify themselves, and ask her to identify herself. After the initial interaction, the agents asked Mendenhall to accompany them upstairs and she complied. There they searched her purse and person and discovered heroin.

Mendenhall sought this evidence to be excluded and was denied.


There was no seizure here because everything appeared voluntarily. The officers approached her. She was not beckoned, or said at any time that the search should discontinue. She voluntarily went upstairs and consented to the search of her purse. Additionally, she never questioned whether she was free to leave.

Additional Notes

A seizure occurs when a reasonable person would believe that the person is not free to leave. Note that this is an objective standard. A stop means that you have been restrained in some way. You have been restrained when you are no longer free to leave. Here there is no evidence to show compelled compliance (no threats, showing weapons, uniforms, etc.). This remains true even if the officer had the intention to detain anyways (as long as the other party didn’t know), and there was no need to tell the defendant that she can decline to participate.

This is an example of a consensual encounter.

Wilson v. State

874 P.2d 215 (Wyo. 1994).


A stop occurs when a reasonable person would not feel free to leave.


The stop occurred before a warrant was obtained. Thus, the stop was a violation of the Fourth Amendment.


Wilson was limping in the middle of the night and assumed that a fight occurred. After asking if Wilson was alright, he smelled alcohol on Wilson’s breath and asked for his ID. The officer then radioed to check the ID, but was interrupted because a fire had occurred. He told Wilson to “stay in the area”. Wilson walked off. Upon coming back, the officer helped Wilson cross the street and told him to wait. The officer then obtained a warrant for Wilson because it turns out that he was implicated in starting the fire.


Approaching Wilson, asking if he was ok, asking for his ID, and telling him to stay in the area (Wilson was leaving), and helping him cross the street (community caretaker) was not a stop because there was no indicator that Wilson was not free to leave. However, when the officer tells Wilson to “go to the corner and wait” this is a stop because this was an order that was complied and enforced by checking on him. In other words, he was not free to leave.

Florida v. Bostick, 501 U.S. 429 (1991).

Even you are not physically free to leave (the aisle is blocked), you are still verbally able to deny compliance. As such, it is not a stop.


The content contained in this article may contain inaccuracies and is not intended to reflect the opinions, views, beliefs, or practices of any academic professor or publication. Instead, this content is a reflection on the author’s understanding of the law and legal practices.

Will Laursen

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