The Fourth Amendment to the U.S. Constitution protects individuals from unreasonable searches and seizures. Generally, evidence found through an unlawful search cannot be used in a criminal proceeding. Behind this principle is the idea that the government cannot invade areas where a person has a reasonable expectation of privacy without a substantial justification. Most searches of private property must be supported by a warrant, which must be based on probable cause and must describe the place to be searched and the people or items to be seized. However, a warrant is not needed in certain situations, such as:
Like a search, an arrest usually must be supported by a warrant based on probable cause. Again, there are some exceptions, such as when an officer witnesses a person committing a crime or has probable cause to believe that a suspect whom they encounter in a public place has committed a felony. Police are entitled to use reasonable force in arresting a suspect, but they cannot use excessive force and may use deadly force only in limited circumstances.
Law enforcement officers may conduct cursory stops and searches, known as “stop and frisks,” without a warrant. These involve a pat down of outer clothing for weapons when an officer reasonably suspects that a person may be armed and dangerous.
Below is a selection of Supreme Court cases involving searches and seizures, arranged from newest to oldest.
Torres v. Madrid (2021)The application of physical force to the body of a person with intent to restrain is a seizure even if the person does not submit and is not subdued.
Kansas v. Glover (2020)
When an officer lacks information negating an inference that a vehicle is driven by its owner, an investigative traffic stop made after running a vehicle's license plate and learning that the registered owner's driver's license has been revoked is reasonable.
The government's acquisition of an individual's cell-site records was a Fourth Amendment search.
The automobile exception does not permit the warrantless entry of a home or its curtilage to search a vehicle therein.
Utah v. Strieff (2016)
The discovery of a valid, pre-existing, and untainted arrest warrant attenuated the connection between the unconstitutional investigatory stop and the evidence seized incident to a lawful arrest.
Without reasonable suspicion, police extension of a traffic stop to conduct a dog sniff violates the Constitution's shield against unreasonable seizures.
When an officer's mistake of law was reasonable, there was a reasonable suspicion justifying a stop under the Fourth Amendment.
Without a warrant, the police generally may not search digital information on a cell phone seized from an individual who has been arrested.
The holding in Randolph is limited to situations in which the objecting occupant is physically present.
Maryland v. King (2013)
When officers make an arrest supported by probable cause to hold for a serious offense and bring the suspect to the station to be detained in custody, taking and analyzing a cheek swab of the arrestee's DNA is, like fingerprinting and photographing, a legitimate police booking procedure that is reasonable under the Fourth Amendment.
Using a drug-sniffing dog on a homeowner's porch to investigate the contents of the home is a search within the meaning of the Fourth Amendment.
U.S. v. Jones (2012)
The government's attachment of a GPS device to a vehicle, and its use of that device to monitor the vehicle's movements, constitutes a search under the Fourth Amendment.
Davis v. U.S. (2011)
Searches conducted in objectively reasonable reliance on binding appellate precedent are not subject to the exclusionary rule.
Kentucky v. King (2011)
The exigent circumstances rule applies when the police do not create the exigency by engaging or threatening to engage in conduct that violates the Fourth Amendment.
The required knowledge component of reasonable suspicion for a school administrator's evidence search is that it raise a moderate chance of finding evidence of wrongdoing.
Arizona v. Gant (2009)
Police may search the passenger compartment of a vehicle incident to a recent occupant's arrest only if it is reasonable to believe that the arrestee might access the vehicle at the time of the search or that the vehicle contains evidence of the offense of arrest.
In a traffic stop setting, the first Terry condition (a lawful investigatory stop) is met whenever it is lawful for police to detain an automobile and its occupants pending inquiry into a vehicular violation. The police need not have cause to believe that any occupant of the vehicle is involved in criminal activity. To justify a patdown of the driver or a passenger during a traffic stop, however, the police must harbor reasonable suspicion that the person subjected to the frisk is armed and dangerous.
Herring v. U.S. (2009)
When police mistakes leading to an unlawful search are the result of isolated negligence attenuated from the search, rather than systemic error or reckless disregard of constitutional requirements, the exclusionary rule does not apply.
When police make a traffic stop, a passenger in the car (not only the driver) is seized for Fourth Amendment purposes and thus may challenge the stop's constitutionality.
Scott v. Harris (2007)
When opposing parties tell two different stories, one of which is blatantly contradicted by the record so that no reasonable jury could believe it, a court should not adopt that version of the facts for the purposes of ruling on a motion for summary judgment. Also, a police officer's attempt to terminate a dangerous high-speed car chase that threatens the lives of innocent bystanders does not violate the Fourth Amendment, even when it places the fleeing motorist at risk of serious injury or death.
Police may enter a home without a warrant when they have an objectively reasonable basis for believing that an occupant is seriously injured or imminently threatened with such injury.
A physically present co-occupant's stated refusal to permit entry to a residence rendered a warrantless entry and search unreasonable and invalid as to them.
A dog sniff conducted during a lawful traffic stop that reveals no information other than the location of a substance that no individual has a right to possess does not violate the Fourth Amendment.
Terry principles permit a state to require a suspect to disclose their name in the course of a Terry stop.
Thornton v. U.S. (2004)
Belton governs even when an officer does not make contact until the person arrested has left the vehicle.
Groh v. Ramirez (2004)
When a warrant did not describe the items to be seized, the fact that the application for the warrant adequately described the items did not save the warrant.
A highway checkpoint where police stopped motorists to ask for information about a recent accident was reasonable under the Fourth Amendment.
U.S. v. Banks (2003)
A 15-to-20-second wait before forcible entry satisfied the Fourth Amendment.
To determine whether an officer had probable cause to make an arrest, a court must examine the events leading up to the arrest, and then decide whether these historical facts, viewed from the standpoint of an objectively reasonable police officer, amount to probable cause.
U.S. v. Drayton (2002)
The Fourth Amendment does not require police officers to advise bus passengers of their right not to cooperate and to refuse consent to searches.
Kyllo v. U.S. (2001)
When the government uses a device that is not in general public use to explore details of a private home that would previously have been unknowable without physical intrusion, the surveillance is a Fourth Amendment search, and it is presumptively unreasonable without a warrant.
The Fourth Amendment does not forbid a warrantless arrest for a minor criminal offense, such as a misdemeanor seatbelt violation punishable only by a fine.
A state hospital's performance of a diagnostic test to obtain evidence of a patient's criminal conduct for law enforcement purposes is an unreasonable search if the patient has not consented to the procedure.
Police officers acted reasonably when, with probable cause to believe that a man had hidden marijuana in his home, they prevented that man from entering the home for about two hours while they obtained a search warrant.
A vehicle checkpoint violates the Fourth Amendment when its primary purpose is indistinguishable from the general interest in crime control.
Bond v. U.S. (2000)
A border patrol agent's physical manipulation of a bus passenger's carry-on bag violated the Fourth Amendment proscription against unreasonable searches.
Florida v. J.L. (2000)
An anonymous tip that a person is carrying a gun is not, without more, sufficient to justify a police officer's stop and frisk of that person.
An individual's presence in a "high crime area", standing alone, is not enough to support a reasonable, particularized suspicion of criminal activity. However, a location's characteristics are relevant in determining whether the circumstances are sufficiently suspicious to warrant further investigation.
Police officers with probable cause to search a car may inspect passengers' belongings found in the car that are capable of concealing the object of the search.
Knowles v. Iowa (1998)
While the authority to conduct a full field search as incident to an arrest was established as a bright line rule under Robinson, that rule should not be extended to a situation in which the concern for officer safety is not present to the same extent, and the concern for destruction or loss of evidence is not present at all.
A no-knock entry is justified when the police have a reasonable suspicion that knocking and announcing their presence would be dangerous or futile under the circumstances, or that it would inhibit the effective investigation of the crime.
An officer making a traffic stop may order passengers to get out of the car pending completion of the stop.
The Fourth Amendment does not require that a lawfully seized defendant be advised that they are free to go before their consent to search will be recognized as voluntary.
Whren v. U.S. (1996)
The temporary detention of a motorist on probable cause to believe that they have violated the traffic laws does not violate the Fourth Amendment prohibition against unreasonable seizures, even if a reasonable officer would not have stopped the motorist without an additional law enforcement objective.
The common-law knock and announce principle forms a part of the Fourth Amendment reasonableness inquiry.
Arizona v. Evans (1995)
The exclusionary rule does not require the suppression of evidence seized in violation of the Fourth Amendment when the erroneous information resulted from clerical errors of court employees.
The police may seize non-threatening contraband detected through the sense of touch during a protective patdown search of the sort permitted by Terry, so long as the search stays within the bounds marked by Terry.
There is no per se rule that every encounter on a bus is a seizure. The appropriate test is whether, taking into account all the circumstances surrounding the encounter, a reasonable passenger would feel free to decline the officers' requests or otherwise terminate the encounter.
In a search extending only to a container within a vehicle, the police may search the container without a warrant when they have probable cause to believe that it holds contraband or evidence.
A criminal suspect's Fourth Amendment right to be free from unreasonable searches is not violated when they give police permission to search their car, and the police open a closed container in the car that might reasonably hold the object of the search.
To constitute a seizure of the person, just as to constitute an arrest, there must be either the application of physical force, however slight, or submission to an officer's show of authority to restrain the subject's liberty.
The use of highway sobriety checkpoints does not violate the Fourth Amendment.
Alabama v. White (1990)
Factors for determining whether an informant's tip establishes probable cause are also relevant in the Terry reasonable suspicion context, although allowance must be made in applying them for the lesser showing required to meet that standard.
When the police have probable cause to arrest a suspect, the exclusionary rule does not bar the use of a statement made by the defendant outside their home, even if the statement is taken after an arrest made in the home in violation of Payton.
Maryland v. Buie (1990)
The Fourth Amendment permits a properly limited protective sweep in conjunction with an in-home arrest when the searching officer has a reasonable belief based on specific and articulable facts that the area to be swept harbors a person posing a danger to those on the arrest scene.
Florida v. Riley (1989)
The Fourth Amendment does not require the police traveling in the public airways at an altitude of 400 feet to obtain a warrant to observe what is visible to the naked eye.
Murray v. U.S. (1988)
The Fourth Amendment does not require the suppression of evidence initially discovered during police officers' illegal entry of private premises if the evidence is also discovered during a later search pursuant to a valid warrant that is wholly independent of the initial illegal entry.
The Fourth Amendment does not prohibit the warrantless search and seizure of garbage left for collection outside the curtilage of a home.
The Fourth Amendment exclusionary rule does not apply to evidence obtained by police who acted in objectively reasonable reliance on a statute authorizing warrantless administrative searches, which is subsequently found to violate the Fourth Amendment.
Arizona v. Hicks (1987)
A truly cursory inspection, which involves merely looking at what is already exposed to view without disturbing it, is not a search for Fourth Amendment purposes and therefore does not even require reasonable suspicion.
Reasonable police regulations related to inventory procedures, administered in good faith, satisfy the Fourth Amendment.
The Fourth Amendment did not prohibit the Environmental Protection Agency from taking, without a warrant, aerial photographs of the defendant's plant complex from an aircraft lawfully in public navigable airspace.
The two justifications for the vehicle exception to the warrant requirement of the Fourth Amendment come into play when a vehicle is being used on the highways or is capable of such use and is found stationary in a place not regularly used for residential purposes. The vehicle is readily mobile, and there is a reduced expectation of privacy stemming from the pervasive regulation of vehicles capable of traveling on highways.
A police officer may not seize an unarmed, non-dangerous suspect by shooting them dead. However, when an officer has probable cause to believe that a suspect poses a threat of serious physical harm, either to the officer or to others, it is not constitutionally unreasonable to prevent escape by using deadly force.
Winston v. Lee (1985)
The reasonableness of surgical intrusions beneath the skin depends on a case-by-case approach, in which the individual's interests in privacy and security are weighed against society's interests in conducting the procedure to obtain evidence for fairly determining guilt or innocence.
The Fourth Amendment prohibition on unreasonable searches and seizures applies to searches conducted by public school officials, but the more lenient standard of reasonable suspicion applies.
Segura v. U.S. (1984)
Securing a dwelling on the basis of probable cause to prevent the destruction or removal of evidence while a search warrant is being sought is not an unreasonable seizure of the dwelling or its contents.
U.S. v. Leon (1984)
The Fourth Amendment exclusionary rule should not be applied to bar the use in the prosecution's case in chief of evidence obtained by officers acting in reasonable reliance on a search warrant issued by a detached and neutral magistrate but ultimately found to be invalid.
Author: Per Curiam
Even when no single piece of evidence in an affidavit was conclusive, the pieces fit neatly together and thus supported the magistrate's determination of probable cause.
Oliver v. U.S. (1984)
The government's intrusion upon open fields is not one of the unreasonable searches proscribed by the Fourth Amendment. No expectation of privacy legitimately attaches to open fields.
Michigan v. Long (1983)
If a state court decision indicates clearly and expressly that it is based on bona fide separate, adequate, and independent state grounds, the Supreme Court will not review the decision. Also, a search of the passenger compartment of an automobile, limited to those areas in which a weapon may be placed or hidden, is permissible if the police officer possesses a reasonable belief based on specific and articulable facts that, taken together with the rational inferences from those facts, reasonably warrant the officer to believe that the suspect is dangerous and that the suspect may gain immediate control of weapons.
Consistent with the Fourth Amendment, it is reasonable for police to search the personal effects of a person under lawful arrest as part of the routine administrative procedure at a police station incident to booking and jailing the suspect.
U.S. v. Place (1983)
The investigative procedure of subjecting luggage to a sniff test by a well-trained narcotics detection dog does not constitute a search within the meaning of the Fourth Amendment.
The rigid two-pronged test under Aguilar and Spinelli for determining whether an informant's tip establishes probable cause for issuance of a warrant is abandoned, and the totality of the circumstances approach that traditionally has informed probable cause determinations is substituted in its place.
U.S. v. Ross (1982)
Police officers who have legitimately stopped a vehicle and who have probable cause to believe that contraband is concealed somewhere in it may conduct a warrantless search of the vehicle that is as thorough as a magistrate could authorize by warrant.
When a policeman has made a lawful custodial arrest of the occupant of an automobile, they may search the passenger compartment of that automobile as a contemporaneous incident of that arrest. The police may also examine the contents of any containers found within the passenger compartment.
Steagald v. U.S. (1981)
An arrest warrant, as opposed to a search warrant, is inadequate to protect the Fourth Amendment interests of persons not named in the warrant when their home is searched without their consent and in the absence of exigent circumstances.
U.S. v. Cortez (1981)
In determining what cause is sufficient to authorize police to stop a person, the totality of the circumstances (the whole picture) must be taken into account. Based upon that whole picture, the detaining officers must have a particularized and objective basis for suspecting the particular person stopped of criminal activity.
When the arrest followed quickly after the search of the defendant's person, it is not important that the search preceded the arrest, rather than vice versa.
The Fourth Amendment prohibits the police from making a warrantless and non-consensual entry into the home of a suspect to make a routine felony arrest.
In the absence of exigent circumstances, police are required to obtain a warrant before searching luggage taken from an automobile properly stopped and searched for contraband.
U.S. v. Caceres (1979)
The exclusionary rule does not require that all evidence obtained in violation of regulations concerning electronic eavesdropping be excluded.
A person aggrieved by an illegal search and seizure only through the introduction of damaging evidence secured by a search of a third person's premises or property has not had any of their Fourth Amendment rights infringed.
When a defendant makes a substantial preliminary showing that a false statement knowingly and intentionally, or with reckless disregard for the truth, was included by the affiant in the warrant affidavit, and if the allegedly false statement is necessary to the finding of probable cause, the Fourth Amendment requires that a hearing be held at the defendant's request.
When the state does not seek to seize persons but instead seeks to seize things, there is no apparent basis in the language of the Fourth Amendment for also imposing the requirements for a valid arrest: probable cause to believe that a third party occupying the place to be searched is implicated in the crime. In other words, valid warrants may be issued to search any property, whether or not occupied by a third party, at which there is probable cause to believe that fruits, instrumentalities, or evidence of a crime will be found.
The exclusionary rule should be invoked with much greater reluctance when the claim is based on a causal relationship between a constitutional violation and the discovery of a live witness than when a similar claim is advanced to support suppression of an inanimate object.
Although the Fifth Amendment may protect an individual from complying with a subpoena for the production of their personal records in their possession, a seizure of the same materials by law enforcement officers is different because the individual against whom the search is directed is not required to aid in the discovery, production, or authentication of incriminating evidence.
U.S. v. Watson (1976)
The cases construing the Fourth Amendment reflect the common-law rule that a peace officer was permitted to arrest without a warrant for a misdemeanor or felony committed in their presence, as well as for a felony not committed in their presence if there was reasonable ground for making the arrest.
State courts were in error in assuming that the Miranda warnings, by themselves, under Wong Sun v. U.S. always purge the taint of an illegal arrest.
Gerstein v. Pugh (1975)
The Fourth Amendment requires a judicial determination of probable cause as a prerequisite to extended restraint of liberty following an arrest.
U.S. v. Edwards (1974)
Once an accused has been lawfully arrested and is in custody, the effects in their possession at the place of detention that were subject to search at the time and place of the arrest may lawfully be searched and seized without a warrant even after a substantial time lapse between the arrest and later administrative processing, on the one hand, and the taking of the property for use as evidence, on the other.
U.S. v. Robinson (1973)
In the case of a lawful custodial arrest, a full search of the person is not only an exception to the warrant requirement of the Fourth Amendment but also a reasonable search under the Fourth Amendment.
When the subject of a search is not in custody, and the state would justify a search on the basis of their consent, the state must demonstrate that the consent was voluntary. Voluntariness is determined from the totality of the surrounding circumstances. While knowledge of a right to refuse consent is a factor to be taken into account, the state need not prove that the person knew that they had a right to withhold consent.
Only in a few specifically established and well delineated situations may a warrantless search of a dwelling withstand constitutional scrutiny. These include when there was consent to the search, the officers were responding to an emergency, the officers were in hot pursuit of a fleeing felon, or the goods ultimately seized were in the process of destruction or were about to be removed from the jurisdiction.
An arresting officer may search the arrestee's person to discover and remove weapons and to seize evidence to prevent its concealment or destruction, and they may search the area within the immediate control of the person arrested, meaning the area from which the person might gain possession of a weapon or destructible evidence.
Spinelli v. U.S. (1969)
A tip was inadequate to provide the basis for a finding of probable cause that a crime was being committed when it did not set forth any reason to support the conclusion that the informant was reliable and did not sufficiently state the underlying circumstances from which the informant drew their conclusions or sufficiently detail the defendant's activities.
Terry v. Ohio (1968)
When a police officer observes unusual conduct that leads him reasonably to conclude in light of his experience that criminal activity may be afoot and that the persons with whom he is dealing may be armed and presently dangerous, when he identifies himself as a policeman and makes reasonable inquiries in the course of investigating this behavior, and when nothing in the initial stages of the encounter serves to dispel his reasonable fear for his own or others' safety, the officer is entitled for the protection of himself and others in the area to conduct a carefully limited search of the outer clothing of such persons in an attempt to discover weapons that might be used to assault him.
Katz v. U.S. (1967)
The government's activities in electronically listening to and recording the defendant's words violated the privacy on which he justifiably relied while using a telephone booth and thus constituted a search and seizure within the meaning of the Fourth Amendment.
Warden v. Hayden (1967)
The exigencies of a situation in which officers were in pursuit of a suspected armed felon in the house that he had entered only minutes before they arrived permitted their warrantless entry and search. Moreover, the distinction prohibiting seizure of items of only evidential value and allowing seizure of instrumentalities, fruits, or contraband is not required by the Fourth Amendment.
A state court does not have a duty to require the disclosure of an informer's identity at a pretrial hearing held for the purpose of determining only the question of probable cause when there was ample evidence in an open and adversary proceeding that the informer was known to the officers to be reliable and that they made the arrest in good faith upon the information that the informer supplied.
The interests in human dignity and privacy that the Fourth Amendment protects forbid any intrusions beyond the body's surface on the mere chance that desired evidence might be obtained. There must be a clear indication that such evidence will be found.
Aguilar v. Texas (1964)
Although an affidavit supporting a search warrant may be based on hearsay information, the magistrate must be informed of some of the underlying circumstances on which the person providing the information relied and some of the underlying circumstances from which the affiant concluded that the undisclosed informant was creditable or their information reliable.
Wong Sun v. U.S. (1963)
Statements made by a suspect in his bedroom at the time of his unlawful arrest were the fruit of the agents' unlawful action and should have been excluded. The narcotics taken from a third party as a result of statements made by the suspect at the time of his arrest were likewise fruits of the unlawful arrest and should not have been admitted. However, when another suspect had been lawfully arraigned and released on his own recognizance after his unlawful arrest and had returned voluntarily several days later when he made an unsigned statement, the connection between his unlawful arrest and the making of that statement was so attenuated that the unsigned statement was not the fruit of the unlawful arrest and was properly admitted.
Mapp v. Ohio (1961)
All evidence obtained by searches and seizures in violation of the federal Constitution is inadmissible in a criminal trial in a state court.
Draper v. U.S. (1959)
Even if the information received by an agent from an informer was hearsay, the agent was legally entitled to consider it in determining whether he had probable cause under the Fourth Amendment and reasonable grounds to believe that the defendant had committed or was committing a violation of the narcotics laws.
Wolf v. Colorado (1949)
In a prosecution in a state court for a state crime, the Fourteenth Amendment does not forbid the admission of relevant evidence, even though obtained by an unreasonable search and seizure.
Olmstead v. U.S. (1928)
Wiretapping was not a search or seizure within the meaning of the Fourth Amendment. (This case was overruled by Katz v. U.S. in 1967.)
Carroll v. U.S. (1925)
The Fourth Amendment recognizes a necessary difference between a search for contraband in a store, dwelling, or other structure for the search of which a warrant may readily be obtained, and a search of a ship, wagon, automobile, or other vehicle that may be quickly moved out of the locality or jurisdiction in which the warrant must be sought.
The government may retain for use as evidence in the criminal prosecution of their owner incriminating documents that are turned over to it by private individuals who procured them through a wrongful search without the participation or knowledge of any government official.
Gouled v. U.S. (1921)
Search warrants may not be used as a means of gaining access to a person's house or office and papers solely for the purpose of making search to secure evidence to be used against them in a criminal or penal proceeding.
Weeks v. U.S. (1914)
The tendency of those executing federal criminal laws to obtain convictions by means of unlawful seizures and enforced confessions in violation of federal rights is not to be sanctioned by the courts that are charged with the support of constitutional rights.