2.   The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized. The Text

3.   The Fourth Amendment originally enforced the notion that “each man’s home is his castle”, secure from unreasonable searches and seizures of property by the government.  It protects against arbitrary arrests, and is the basis of the law regarding search warrants, stop-and-frisk, safety inspections, wiretaps, and other forms of surveillance, as well as being central to many other criminal law topics and to privacy law.

4.   The ultimate goal of this provision is to protect people’s right to privacy and freedom from arbitrary governmental intrusions. Private intrusions not acting in the color of governmental authority are exempted from the Fourth Amendment.

5.   To have standing to claim protection under the Fourth Amendment, one must first demonstrate an expectation of privacy, which is not merely a subjective expectation in mind but an expectation that society is prepared to recognized as reasonable under the circumstances. Standing

6.   The protection under the Fourth Amendment can be waived if one voluntarily consents to or does not object to evidence collected during a warrantless search or seizure. Voluntary Consent

7.   A search under Fourth Amendment occurs when a governmental employee or agent of the government violates an individual's reasonable expectation of privacy.  Strip searches and visual body cavity searches, including anal or genital inspections, constitute reasonable searches under the Fourth Amendment when supported by probable cause and conducted in a reasonable manner.  A dog-sniff inspection is invalid under the Fourth Amendment if the inspection violates a reasonable expectation of privacy. Electronic surveillance is also considered a search under the Fourth Amendment What is a Search

8.   A seizure of a person, within the meaning of the Fourth Amendment, occurs when the police's conduct would communicate to a reasonable person, taking into account the circumstances surrounding the encounter, that the person is not free to ignore the police presence and leave at his will.

9.   Two elements must be present to constitute a seizure of a person.  First, there must be a show of authority by the police officer. Presence of handcuffs or weapons, the use of forceful language, and physical contact are each strong indicators of authority.  Second, the person being seized must submit to the authority. Two part test

10.   An arrest warrant is preferred but not required to make a lawful arrest under the Fourth Amendment. A warrantless arrest may be justified where probable cause and urgent need are present prior to the arrest. Warrants

11.   Probable cause is present when the police officer has a reasonable belief in the guilt of the suspect based on the facts and information prior to the arrest. Probable Cause

12.   a warrantless arrest may be legitimate in situations where a police officer has a probable belief that a suspect has either committed a crime or is a threat to the public security. Also, a police officer might arrest a suspect to prevent the suspect’s escape or to preserve evidence. A warrantless arrest may be invalidated if the police officer fails to demonstrate exigent circumstances. Warrantless Arrest

13.   The ability to make warrantless arrests are commonly limited by statutes subject to the due process guaranty of the U.S. Constitution. A suspect arrested without a warrant is entitled to prompt judicial determination, usually within 48 hours.

14.   To obtain a search warrant or arrest warrant, the law enforcement officer must demonstrate probable cause that a search or seizure is justified. An authority, usually a magistrate, will consider the totality of circumstances and determine whether to issue the warrant. Warrant requirements

15.   Stop and Frisk  Terry v. Ohio [392 U.S. 1, 88 S.Ct. 1968, 20 L.Ed.2d 889 (1968)]  A police officer witnessed three men pacing in front of a jewelry store and suspected that a robbery was being planned. He approached the men and identified himself, then performed frisks of defendants Chilton and Terry and discovered illegal concealed weapons. Defendants were convicted and appealed, claiming that the frisk violated their Fourth Amendment right against unlawful searches and seizures.  The Supreme Court upheld the conviction, finding that when a law enforcement officer has "reasonable grounds" for suspecting that a criminal suspect may be armed, he may pat down the outer layer of the suspect's clothing for weapons. The ruling held that the Fourth Amendment protection against unreasonable searches and seizures is not violated when a pat down is performed based on reasonable suspicion for the purpose of ensuring officer safety.

16.   Dolly Mapp's home was searched by seven police officers who claimed they had a warrant but never produced it. The police alleged that an informant had told them that a bombing suspect and gambling paraphernalia were inside the residence. Neither were found but the police confiscated what they termed obscene materials. Mapp was convicted of possessing obscene materials and imprisoned.  Justice Tom Clark wrote that the lack of an exclusionary rule left states without an effective means of dealing with unreasonable searches and seizures. Mapp v. Ohio 367 U.S. 643 (1961) The case used for Incorporation

17.   In this case, a reasonable expectation of privacy test was created. Federal agents had attached a listening device to the outside of a phone booth that was know to be often used by Mr. Katz. Evidence of his end of the conversations obtained by the listening device was admitted in his trial in which he was accused of transmitting wagering information by telephone. The lower court held that this was not a search because the wall of the phone booth had not been physically penetrated. Their ruling was based on Olmstead v. United States (1928) in which the Supreme Court had ruled that a tap of a telephone did not constitute a search.  In Katz, the Supreme Court ruled that the electronic "listening to" and recording of Mr. Katz's conversation violated the privacy upon which he justifiably relied and thus constituted a search and seizure under the Fourth Amendment. Justice John M. Harlan, in a concurring opinion, established a two part test for this right of privacy. First, a person must exhibit an actual expectation of privacy. Second, this expectation must be one that society recognizes as "reasonable". Katz v. United States (1967)

18.   Do you have an expectation of privacy in a public restroom? Would most people find it objectively reasonable to expect privacy in the restroom?  Therefore, the installation of a hidden video camera by the police in a public restroom would be considered a "search" and would be subject to the Fourth Amendment's requirement of reasonableness.  On the other hand, if an officer stops a car and, when talking to the driver, happens to notice a weapon on the passenger seat, there's been no search under the Fourth Amendment. That's because, even if the driver somehow considered the passenger seat to be a private place, society isn't willing to extend privacy protections to that particular location. In other words, there's no objectively reasonable expectation of privacy with respect to the gun because it was in plain view.  A good example of how this works comes from a U.S. Supreme Court case in which the court held that a bus passenger had a legitimate expectation of privacy in an opaque carry-on bag positioned in a luggage rack above the passenger's head. The Court held that the physical probing by the police of the bag's exterior for evidence of contraband constituted a search subject to Fourth Amendment limitations. (Bond v. U.S. (2000).) Expectation of Privacy

19.   Private security personnel have at times outnumbered police officers in the United States by three to one. As a result, whether you're shopping in a supermarket or a pharmacy, working in an office building, or visiting a friend in a housing project, you may be more likely to be confronted by a security guard than by a police officer.  Does the 4 th Amendment apply?  The Fourth Amendment doesn't apply to searches carried out by non-governmental employees (like private security guards) who aren't acting on the government's behalf.  For example, assume that a shopping mall security guard acting on a pure hunch searches a teenager's backpack. Inside the backpack the guard finds a baggie containing an illegal drug. The guard can detain the teenager, call the police, and turn the drug over to a police officer. The drug is admissible in evidence, because the search was conducted by a private security guard acting on his own, rather than at the officer's direction. Private Security Officers

20.   For example, assume that a shopping mall security guard acting on a pure hunch searches a teenager's backpack. Inside the backpack the guard finds a baggie containing an illegal drug. The guard can detain the teenager, call the police, and turn the drug over to a police officer. The drug is admissible in evidence, because the search was conducted by a private security guard acting on his own, rather than at the officer's direction.

21.   The exclusionary rule. If, upon review, a court finds that an unreasonable search occurred, any evidence seized as a result of it cannot be used as direct evidence against the defendant in a criminal prosecution. This principle, established by the U.S. Supreme Court in 1961, has come to be known as the exclusionary rule.  To this day, many commentators criticize the exclusionary rule on the ground that it unfairly "lets the criminal go free because the constable has erred." But the rule's supporters argue that excluding illegally seized evidence is necessary to deter police from conducting illegal searches. According to this deterrence argument, the police are less likely to conduct improper searches if the resulting evidence can't be used to convict the defendant. (There are, however, exceptions to the exclusionary rule—for one, see Police Searches and the Good Faith Exception.)  Fruit of the poisonous tree doctrine. Not only is evidence that's the product of an illegal search generally inadmissible in court, but so too is additional evidence that derived from the initial evidence. This principle is colorfully known as the "fruit of the poisonous tree" doctrine. The "tree" is the evidence that the police illegally seize in the first place; the "fruit" is the second-generation product of the illegally seized evidence. Both tree and fruit are typically inadmissible at trial. (For more, see Fruit of the Poisonous Tree.) When A Search Violates the Fourth Amendment

22.   Officer Wiley arrests Hy Lowe for selling phony telephone cards. A judge rules that Officer Wiley illegally entered Lowe's home and improperly seized a map showing the location where Lowe hid the phone cards. Officer Wiley then found the phone cards in that location. Because Officer Wiley obtained the map through an illegal search, it and the phone cards are inadmissible. The phone cards are the fruit of the unlawful search.

23.   Not always end of story. Some defendants believe that if they can show that a search was illegal, the case must be dismissed. Not true. If a prosecutor has enough other evidence to prove the defendant guilty, the case can continue. Also, the illegally-seized evidence can generally be considered by a judge when deciding on an appropriate sentence following conviction and admitted in civil and deportation cases. In some circumstances, a prosecutor can use such evidence to impeach (attack the credibility of) a defendant who testifies at trial.