The Fourth Amendment: An Overview of Constitutional Searches and Seizures

The Warrant Clause

"...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"

In Miller v. United States (1958) the Court held

"The requirement of prior notice of authority and purpose before forcing entry into a home is deeply rooted in our heritage, and should not be given grudging application. ... Every householder, the good and the bad, the guilty and the innocent, is entitled to the protection designed to secure the common interest against unlawful invasion of the home." Because the officers did not give notice before breaking into Miller's home, the subsequent arrest was unlawful and the evidence seized should have been suppressed.

Reasonableness Clause

"The right of the people to be secure in their persons, houses, papers and effects, against unreasonable searches and seizures shall not be violated"

Association with other known criminals is another factor that may contribute to the finding of probable cause. In United States v. Di Re (1948), the Court said that

"one who accompanies a criminal to a crime rendezvous cannot be assumed to be a bystander," and that one's presence with others engaged in criminal activity can contribute to a finding of probable cause.

In instances in which the preponderance of evidence suggests the defendant's guilt and the "tainted" or illegal evidence is not critical to proving the case against the defendant, the harmless error exception applies. This standard was first set forth by the Court in Chapman v. California (1967) when it ruled

"that before a federal constitutional error can be held harmless, the court must be able to declare a belief that it was harmless beyond a reasonable doubt."

When police violate a person's constitutional rights by conducting an unlawful stop and frisk or search and seizure, two serious consequences may occur:

(1)the evidence may be excluded from court and (2)internal sanctions as well as civil and criminal liability may be incurred.

Guidelines established by Terry v. Ohio determining whether a stop or frisk is valid include the following:

1. Suspicious circumstances, that is, conduct that leads an experienced officer to believe that a crime is about to be committed and that the person about to commit the crime may be armed and dangerous. 2. While investigating the behavior, officers identify themselves as police officers and make reasonable inquiries, for example, "What is your name?" 3. If officers are still suspicious and suspect the person may be armed and dangerous, they may conduct a limited search of the person's outer clothing to protect themselves and others in the area.

The exclusionary rule

1. helps preserve judicial integrity by preventing judicial agreement in denying a person's Fourth Amendment rights, 2. deters police misconduct by making improperly obtained evidence inadmissible in court, 3. and protects citizens' constitutional "right to privacy.

In certain instances, exigent circumstances may justify an entry by police without first announcing their presences, including when

1. victims or hostages may be inside, 2. when a crime is actually in progress, 3. when evidence or contraband may be destroyed, 4. or when making the officers' presence known would place them in danger. In such instances officers may ask for special conditions to be attached to a warrant, such as making an unannounced entrance or carrying out a search at night.

Reasonableness is determined by considering the totality of circumstances in each individual case. It is the most commonly used method in the U.S.

Case-by-case method

Terry v. Ohio (1968)

Detective Martin McFadden had been a police officer with the Cleveland Police Department for 39 years, and 35 of that as a detective. To untrained eyes, the men Detective McFadden saw outside the jewelry store that day were merely standing there talking, but McFadden sensed more. On the basis of his experience, he suspected they were casing the store, planning to rob it, and possibly were armed. He watched as the two men walked back and forth, looking into the store window, walking to the corner, and then returning to talk to each other. Another man joined them, then went inside the store, returned, and the routine continued. When the three men were together outside the store, McFadden approached them, identified himself as a police officer, asked their names and grabbed one of the men, placing him between himself and the other two. He quickly patted down the outer clothing of that man, later identified as John Terry, and felt what could be a gun in Terry's pocket, but he could not remove it. He ordered the three into the store at gunpoint, removed Terry's coat, and took a .38-caliber revolver from the pocket. When he patted down the other men, he found a revolver in the coat of one. Both men were charged with carrying concealed weapons. The defense lawyers argued the guns had been seized illegally, so could not be used as evidence. The Ohio trial judge found both suspects guilty, and Terry and the other man appealed their conviction to the U.S. Supreme Court. Before this case reached the Supreme Court, the other man died, so the decision refers to only defendant Terry. The legal issue before the Court was simply phrased: "whether it is always unreasonable for a policeman to seize a person and subject him to a limited search for weapons unless there is probable cause for an arrest." The U.S. Supreme Court upheld the Ohio court verdict, ruling Detective McFadden had acted reasonably because his experience and training supported his suspicion that the three men were planning a robbery; the robbery would probably involve weapons; and nothing occurred to make him think differently. He had to act quickly when he saw the three men gather at the store. Therefore, such a search is reasonable under the Fourth Amendment, and any weapons seized may properly be introduced in evidence against the person from whom they were seized.

MYTH: Anytime a person is legally stopped by an officer, that officer has the right to conduct a frisk to discover if that person is concealing any contraband.

Fact A frisk is a limited pat-down search for weapons for the protection of the officer and others. It is not automatically permitted with a stop but only when the officer suspects the person is armed and dangerous.

Weeks v. United States (1914)

Fremont Weeks was charged with using the mail for illegal gambling purposes after officers searched his home on two different occasions without a warrant. The issue was simply whether illegally obtained evidence is admissible in court, to which the Supreme Court held it was not, stating that the right to be free from unreasonable searches and seizures under the Fourth Amendment applies: to all invasions on the part of the government and its employees of the sanctity of a man's home and the privacies of life. It is not the breaking of his doors and the rummaging of his drawers that constitutes the essence of the offense; but it is the invasion of his indefeasible right to personal security, personal liberty and private property. The Weeks Court specifically excluded illegally obtained evidence from use in federal prosecutions.

United States v. Parker (1994)

Held that UPS employees could open, without warrants, packages and inspect their contents whenever a customer insured a package for more than $1000.

United States v. Ross (1982)

Held that an airline employee who inspected the defendant's luggage according to the FAA regulations was acting in a government capacity and was governed by the Fourth Amendment.

Issue: The police received an anonymous letter outlining specific details about the Defendants being involved in drug trafficking, later corroborated by their actions. Is the letter enough for probable cause?

Holding: Yes. Abandoned the two prong test and replaced it with the totality of the circumstances. Made the establishment of probable cause by use of informants easier for police.

Issue: An affidavit provided by police officers in support of a warrant stated that they had received information from an unidentified informant that Aguilar possessed drugs at his residence. Was this enough for probable cause?

Holding: Yes. Established a two prong test for informants: 1st prong: tested the informants creditability. 2nd prong: tested the informant's basis of knowledge and reliability of the information provided.

This two-pronged approach was abandoned in 1983 in

Illinois v. Gates

Exceptions to the Exclusionary Rule There are four exceptions to the exclusionary rule:

Inevitable discovery doctrine Valid independent source Harmless error Good faith

Since the 1960's, the Court has broadened government's power by adopting the reasonableness Fourth Amendment approach.

It sees the two clauses as separate, distinct, and addressing two separate situations. This clause makes warrantless searches and seizures valid and constitutional when they are sensible.

The Court has held that because this detention (a stop) is not an arrest (it is a stop), no Miranda warning need be given. For this reason, a driver stopped by the police for a traffic violation need not be advised of his or her

Miranda rights—although the driver is not free to go for a short time, he or she will be, so it is not an arrest.

Does the exclusionary rule apply to evidence seized as a result of an inaccurate police record (an arrest warrant)?

No. Court employees, not the police, were responsible for the inaccurate record. The application of the exclusionary rule would have no deterrent effect on the police, which is the objective of the rule.

May evidence obtained in violation of the Fourth Amendment be used in state court?

No. Evidence obtained through a violation of the Fourth Amendment cannot be used in state court, just as it cannot be used in federal court. This provision has been incorporated.

Should the exclusionary rule apply to evidence discovered while executing a search warrant that officers reasonably relied upon despite its lack of probable cause?

No. Excluding this evidence would serve no purpose in deterring intentional police misconduct when they reasonably rely upon a search warrant issued by a judge, and therefore, the cost to society would be too great not to allow the evidence into trial.

Does an officer violate the Fourth Amendment when he seizes a person and searches that person for weapons on facts that do not rise to the level of probable cause?

No. The Fourth Amendment prohibits unreasonable searches and seizures. Balancing the need for effective law enforcement and the safety of officers, a person may be subjected to a brief detention and a frisk when the objective facts support the belief that: 1. a crime is occurring, 2.has occurred, 3 or is about to occur and that the person detained may be armed and dangerous.

Should evidence be excluded from trial when the suspect gives information in violation of his Sixth Amendment right to counsel that leads to the discovery of that evidence?

No. When the prosecution is able to show that the evidence would have been discovered through lawful means anyway, it is admissible.

Issue (United States v. Jacbosen (1984) is it a violation of the fourth amendment for any employee of a private company to open and inspect the contents of a package

No. the actions were of a private person, not acting at the direction or with the knowledge of a government official

A police officer will always need a warrant to conduct a search

No. the constitution has ben interpreted to allow for warrantless searches under a few well-delineated exceptions

There are two clauses that are important to the Fourth Amendment in regards to search and seizure:

Reasonableness Clause "The right of the people to be secure in their persons, houses, papers and effects, against unreasonable searches and seizures shall not be violated" The Warrant Clause "...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 landmark case for stop-and-frisk law is

Terry v. Ohio (1968),

Mapp v. Ohio (1961)

The Fourteenth Amendment forbids states to "deprive any person of life, liberty or property, without due process of law," and after Weeks, the question arose as to whether the exclusionary rule should be applied at the state level. In Mapp, the defendant refused to allow officers without a warrant into her home. The officers had information that a suspect was hiding in her basement and returned three hours later with reinforcements. When Mapp did not respond, officers broke in and searched the home, finding obscene materials. The Supreme Court, overruling Wolf, held that "all evidence obtained by searches and seizures in violation of the Constitution are by the same authority inadmissible in a state court." Reversing the trial court, the Supreme Court stated: Since the Fourth Amendment's right of privacy has been declared enforceable against the States through the Due Process Clause of the Fourteenth Amendment, it is enforceable against them by the same sanction of exclusion as is used against the Federal government. Were it otherwise, then just as without the Weeks rule the assurance against unreasonable searches and seizures would be "a form of words," valueless and undeserving of mention in a perpetual charter of inestimable human liberties, so too, without that rule the freedom from state invasions of privacy would be ephemeral.

The Leon case held that the exclusionary rule would be applied to only the following three situations in searches conducted pursuant to a warrant:

The magistrate abandoned the prescribed detached and neutral role in issuing the warrant. The officers were dishonest or reckless in preparing their affidavit or the search warrant. The officers could not have harbored an objectively reasonable belief in the existence of probable cause.

What if the private party had agreed to go in and get the item from the house, or the private security guard had agreed search the person for the police

Then arguably this private person although not employed by the government has become an agent of the government and then the fourth amendment would apply

Store detectives are not controlled by the Fourth Amendment. Why?

They are not government agents, and the Constitution was established to limit the power of government and its agents.

Is an alert by a well-trained narcotics detection dog certified to detect illegal contraband sufficient to establish probable cause for the search of a vehicle?

Yes. Probable cause is a fluid concept that takes the totality of the circumstances into account. Each side should put their best case forward, presenting the evidence at hand, to show probable cause does or does not exist.

After knocking and announcing a search warrant, is 15 to 20 seconds a reasonable amount of time to wait before forcing entry?

Yes. When looking at the totality of the circumstances and the particular exigency facing the officers, waiting 15 to 20 seconds was enough time. "The officers' 15- to 20-second wait before forcible entry satisfied the Fourth Amendment.... After 15 to 20 seconds without a response, officers could fairly have suspected that Banks would flush away the cocaine if they remained reticent. ... This Court's emphasis on totality analysis leads it to reject the government's position that the need to damage property should not be part of the analysis of whether the entry itself was unreasonable." The Court stated that reasonableness must be viewed under the totality of the circumstances, noting that an important fact was not the time that it would have taken Banks to open the door but, rather, the time it would take to destroy the evidence.

The question of how long officers must wait after knocking and announcing themselves before forcibly entering has been before the courts. In United States v. Banks (2003), the Court determined that

a 15-to-20-second wait after knocking and announcing before a forcible entry was sufficient to satisfy the Fourth Amendment. In this case, officers armed with a search warrant arrived at suspected drug dealer Lashawn Banks' apartment and followed standard procedure, knocked loudly on the front door, and stated, "Police search warrant." After waiting 15 to 20 seconds without hearing anything from inside the apartment, police forcibly entered with a battering ram.

Silverthorne Lumber Co. v. United States (1920) extended the exclusionary rule delineated in Weeks (1914). In this case,

a U.S. marshal unlawfully entered and searched the Silverthorne Lumber Company's offices and illegally took books and documents. When the company demanded their return, the government did so, but not before making copies of the documents. These copies were later impounded by the district court and became the basis for a grand jury indictment. A subpoena was then served on the company to produce the originals. When the company refused, it was convicted of contempt of court. The Supreme Court, however, reversed the conviction saying, "The essence of a provision forbidding the acquisition of evidence in a certain way is that not merely evidence so acquired shall not be used before the Court, but that it shall not be used at all." In other words, once the primary source (the "tree") is proved to have been obtained unlawfully, any secondary evidence derived from it (the "fruit") is also inadmissible.

probable cause is the key determination of whether

a judge will grant officers a warrant to search or arrest.

Probable Cause must be established before

a lawful search or arrest can be made.

In Draper v. United States (1959)

a narcotics officer received information from a reliable informant that heroin was being transported on a train by a person the informant described in great detail, including what he would be wearing, even the fact he "walked real fast." The officers set up surveillance and arrested a man matching the description. Heroin and a syringe were found in a search incident to the arrest. The Supreme Court at that time held that information from a reliable informant, corroborated by the police, upheld a determination of probable cause.

In other cases, the illicit activity occurs primarily at night—illegal gambling, for example. In such cases, the officers can ask the judge to include a provision that allows them to execute the warrant at night

a nightcap(ped) warrant. All that the officer needs to show is a reasonable suspicion that, to preserve evidence or protect officers, a nighttime search is necessary, a similar standard of proof to the no-knock entry request.

For example, the police may have no authority to act when driving by someone who appears to be merely walking along a public sidewalk, but if the officer sees something in the rearview mirror that causes him or her to become suspicious, the situation could justify

a stop and possibly a frisk. Depending on what results from these interactions, if probable cause develops, the stop could escalate to the level of an arrest and then a search incident to that arrest, and it could all happen in a matter of moments.

An action such as fleeing from the police will certainly raise the circumspection of law enforcement and contribute heavily in establishing reasonable suspicion. In Illinois v. Wardlow (2000),

a stop was held lawful when the suspect was in a high-crime area and fled upon seeing the police. The Court held that the individual's flight at the sight of police was enough to provide reasonable suspicion for an investigatory stop.

In Rawlings v. Kentucky (1980)

a suspect admitted that the contents of her purse (drugs) belonged to her, and the court found this admission to be sufficient probable cause for the police to arrest her.

If evidence that might otherwise fall victim to the exclusionary rule is obtained from a valid, independent source, that evidence can be admitted. In Segura v. United States (1984),

although evidence discovered during an illegal entry into an apartment was excluded, evidence later found in the apartment while a search with a warrant was being executed was admissible because the warrant was obtained with information totally unconnected with the illegal entry.

Police officers also may refuse to allow people to enter their residence while the police obtain a search warrant. In Illinois v. McArthur (2001), the Court held that

although preventing a suspect from entering his or her own home constituted a seizure of that person, if the warrant was being obtained as rapidly as possible, such police action was reasonable. The Court explained that exigent circumstances existed and the seizure of the suspect was as brief and unintrusive as possible.

The knock-and-announce rule protects

citizens' rights, and it can enhance officer safety in executing a warrant. For example, a plainclothes police sergeant executing a search warrant was killed by a suspect who claimed to have fired on someone breaking into his house. Although the police asserted they identified themselves as police, the prosecution was unable to prove beyond a reasonable doubt that the resident was not acting in self-defense.

The exclusionary rule applies only in

criminal trials in which a constitutional right has been violated. Several important exceptions to the exclusionary rule have evolved from common law by the U.S. Supreme Court.

Once signed by a judge, the warrant becomes an order for the police to carry out the search or arrest. Unless special conditions have been included in the warrant (no-knock warrant or nightcap warrant), government agents must carry out the warrant during

daylight hours and must also identify themselves as officers and state their purpose.

The officers may use reasonable force to execute the warrant if they are

denied entrance or if no one is home.

Facts and evidence obtained after a search or arrest can not be used to

establish probable cause.

In State v. Heald (1973), the court ruled that

evidence at a burglary scene, including a distinctive tire tread left in the snow, provided sufficient probable cause to arrest when the police approached the suspect vehicle and the driver drove away.

attenuation doctrine

evidence obtained as a result of a previous illegality may be admissible at trial if it is so far removed, through time and space, from the original violation that any "taint" has dissipated

The fruit of the poisonous tree doctrine states that

evidence obtained as a result of a previous illegality must be excluded from trial. This extension of the exclusionary rule is based on the same rationale as the exclusionary rule itself, that is, to deter illegal police activity and to preserve the integrity of the court.

inevitable discovery doctrine

exception to exclusionary rule deeming evidence admissible even if seized in violation of the Fourth Amendment when it can be shown that the evidence would have inevitably been discovered through lawful means

Government agents who have probable cause to believe evidence of a crime is located at a specific place or that an individual is involved in a crime must

go before a neutral and detached magistrate (judge) and swear under oath who or what they are looking for and where they think it can be found.

who is regulated by the fourth amendment

government agencies state agencies county sherifs local police public schools and colleges local, count, and municipal bodies of government

United States v. Tapley (2016)

held that a computer repair technician did not act as a government official when he found some unusual pictures of children on a computer; reported it to the police , who found no violation; and then continued the search on his own of the computer eventually finding chills pornography

A stop differs from an arrest, in

in that when arrested, a person is not free to go.

A stop

is a brief detention of a person based on specific and articulable facts for the purpose of investigating suspicious activity.

A frisk

is a limited pat-down search for weapons for the protection of the officer and others. It is not automatically permitted with a stop but only when the officer suspects the person is armed and dangerous.

The constitutional requirement of reasonableness is required before one

is stopped or frisked, just as it is before one is arrested and searched.

no-knock warrant.

issued when officers want to make an unannounced entrance because they are afraid evidence might be destroyed or officer safety requires it

In Michigan v. Summers (1981), the Court ruled that

it is constitutional to detain the occupants of a premises during the execution of a search warrant while a proper search is being conducted.

Officers can break a door or window or break a car window to make an arrest or to execute a search warrant if necessary, but the general rule is that law enforcement officers must first

knock and announce their authority and purpose before breaking into a dwelling.

If officers want to make an unannounced entrance because they fear evidence might be destroyed or officer safety requires it, they can request a

no-knock warrant.

good faith

officers are unaware that they are acting in violation of a suspect's constitutional rights

However, if the suspect is present at a recent crime, that presence may be sufficient, as was the case in State v. Mimmovich (1971), in which

officers found the suspects of a burglary in suspiciously close proximity to the burglarized dwelling immediately after it occurred. If suspects were crawling out a window during a suspected burglary, that action could be sufficient.

Probable cause determines when

officers may execute lawful searches and arrests with or, in some cases, without a warrant.

Probable cause to arrest means

officers reasonably believe that a crime has been committed by the person they seek to arrest.

Probable cause to search means

officers reasonably believe that evidence, contraband, or other items sought are where police believe these items to be.

All warrants are to be based on

on probable cause.

If probable cause is not present

police cannot act, if they do consequences will ensue

The fact that someone has been involved in past criminal activity (Beck v. Ohio, 1964) or fails to protest his or her arrest is insufficient in itself to infer

probable cause to support an arrest.

Physical evidence may establish

probable cause.

In United States v. Arvizu (2002), the Supreme Court reaffirmed that

reasonable suspicion (fleeing from the law) may be part of the totality of the circumstances. Arvizu also reaffirmed the importance of an officer's training and experience in determining the existence of reasonable suspicion, as the Court explained, "This process [of looking at the totality of the circumstances] allows officers to draw on their own experience and specialized training to make inferences from and deductions about the cumulative information available to them that 'might well elude an untrained person.'"

Probable cause is stronger than

reasonable suspicion. It can legally justify searches and arrests with or without a warrant.

As long as probable cause exists to arrest, search incident to arrest is

reasonable.

Private individuals or agencies are not

regulated by the Fourth Amendment.

Nix v. Williams (1984)

resulted in the inevitable discovery doctrine. To understand how this doctrine came about, one must backtrack to a previous trial, Brewer v. Williams (1977). The trials involved the same case and defendant (Williams) but different prosecutors. The case involved in both trials began on Christmas Eve of 1968, when 10-year-old Pamela Powers disappeared while attending an event at a YMCA with her family in Des Moines, Iowa. Shortly after she was reported missing, a 14-year-old boy reported having been asked by a YMCA resident to hold several doors open for him while the man loaded a bundle from the building into a car. The boy reported seeing two skinny white legs within the bundle An arrest warrant was subsequently issued for Robert Williams, a YMCA resident and an escapee from a psychiatric hospital. Williams eventually turned himself in to police in Davenport, Iowa. An agreement was reached through Williams's lawyer that the defendant would be returned by police to Des Moines. All agreed that Williams would not be interrogated in any way during the 160-mile trip. However, during the drive, knowing that Williams was a psychiatric patient and that he possessed a strong religious faith, one officer said the following to Williams (known as the "Christian Burial Speech"): I want to give you something to think about while we're traveling down the road. ... Number one, I want you to observe the weather conditions, it's raining, it's sleeting, it's freezing, driving is very treacherous, visibility is poor, it's going to be dark early this evening. They are predicting several inches of snow for tonight, and I feel that you yourself are the only person that knows where this little girl's body is, that you yourself have only been there once, and if you get a snow on top of it, you yourself may be unable to find it. And since we will be going right past the area on the way to Des Moines, I feel that we could stop and locate the body, that the parents of this little girl should be entitled to a Christian burial for the little girl who was snatched away from them on Christmas Eve and murdered. And I feel we should stop and locate it on the way rather than waiting until morning and trying to come back out after a snowstorm and possibly not being able to find it at all. The detective told Williams that he did not want an answer, but that he just wanted Williams to think about it as they drove. Williams eventually directed the officers to the little girl's body. Although the lower courts admitted Williams's damaging statements into evidence, the Supreme Court in Brewer v. Williams affirmed the court of appeals' decision that any statements made by Williams could not be admitted against him because the way they were elicited violated his constitutional right to counsel. This case is also discussed in the section dealing with confessions and the right to counsel. The Court said: The pressures on state executive and judicial officers charged with the administration of the criminal law are great, especially when the crime is murder and the victim a small child. But it is precisely the predictability of those pressures that makes imperative a resolute loyalty to the guarantees that the Constitution extends to us all. The Court granted Williams a second trial without his damaging statements being admissible. At this trial (Nix v. Williams), the Court allowed the body to be admissible evidence, not because it was found as a result of the improper questioning by the police, but because an independent search party would have eventually discovered it: If the government can prove that the evidence would have been obtained inevitably and, therefore, would have been admitted regardless of any overreach by the police, there is no rational basis to keep that evidence from the jury in order to ensure the fairness of the trial proceedings. Williams was convicted.

In Rochin v. California (1952), the Court held that

searches that "shock the conscience" are a violation of due process, and any evidence so obtained will, therefore, be inadmissible in a court of law. It is important to note that this "shock the conscience" criterion is a different standard under due process than that which was discussed previously. The standard here deals with due process issues that arise from specific acts by officers, not from those enacted by a legislature into law. In Rochin, the police took the suspect to the hospital and had his stomach pumped after observing him swallow pills. Morphine capsules were recovered in this search, but in invoking the exclusionary rule, the Court stated: [T]he proceedings by which this conviction was obtained do more than offend some fastidious squeamishness or private sentimentalism about combating crime too energetically. This is conduct that shocks the conscience. Illegally breaking into the privacy of the petitioner, the struggle to open his mouth and remove what was there, the forcible extraction of his stomach's contents—this course of proceeding by agents of the government to obtain evidence is bound to offend even hardened sensibilities. They are methods too close to the rack and screw to permit constitutional differentiation. Thus, in Rochin, the evidence was excluded as a result of a due process violation, not by the application of the exclusionary rule. At the time of the decision, the exclusionary rule had not yet been applied to the states through Mapp.

without probable cause

seized evidence may be inadmissible in court, arrest determined illegal, and officers and others held liable for such illegality

Observational probable cause is derived from a government agent's personal experiences—what officers perceive through their own

senses of sight, hearing, smell, touch, and taste.

Admissions made to a police officer, verbally or through actions, may provide

sufficient observational probable cause or lead to a finding of probable cause under the totality of the circumstances analysis.

The law of stop and frisk permits officers to act on their

suspicions rather than to turn away, awaiting that infrequent, obvious crime to be committed before their eyes.

In Murray v. United States (1988),

the Court again held that evidence initially seen during an illegal search but later recovered under a valid warrant would be admissible. In this case, the police initially broke in without a warrant but returned later with a valid warrant not using what they had seen during the initial break-in to support the probable cause in the warrant.

In Spinelli v. United States (1969),

the Court faced the question of whether probable cause existed to support a search warrant that uncovered evidence to convict Spinelli of running a gambling operation. This case examined the determination that had deemed an informant reliable despite the absence of facts to support the perceived reliability. Even more important to the decision, the Court continued, was that, "The tip does not contain a sufficient statement of the underlying circumstances from which the informer concluded that Spinelli was running a bookmaking operation. We are not told how the FBI's source received his information—it is not alleged that the informant personally observed Spinelli at work or that he had ever placed a bet with him. Moreover, if the informant came by the information indirectly, he did not explain why his sources were reliable. In the absence of a statement detailing the manner in which the information was gathered, it is especially important that the tip describe the accused's criminal activity in sufficient detail that the magistrate may know that he is relying on something more substantial than a casual rumor circulating in the underworld or an accusation based merely on an individual's general reputation." Thus, Spinelli refined how a judge should evaluate the two prongs of Aguilar when determining the existence of probable cause stemming from an informant.

In United States v. Sokolow (1989)

the Court justified a warrantless investigative stop as reasonable under the Fourth Amendment because, given the totality of the circumstances present, sufficient reasonable suspicion existed. reasonable suspicion is more than an experienced officer's hunch or intuition, and more than mere whim, caprice, or idle curiosity; it is a rational inference taken from specific and articulable facts, and viewed objectively using the totality of the circumstances. articulable facts are descriptions or actions described in clear, distinct statements. Although Sokolow dealt with another issue, that of "drug courier profiles," this case demonstrates that the totality of circumstances will be relied on in determining the constitutional justification for intrusion by the police.

And in Harrington v. California (1969),

the Court ruled that the evidence should be examined as a whole, and that if overwhelming untainted evidence supported the conviction, or if the error involved a well-established element of the crime, then the error would be considered "harmless."

Florida v. Harris (2013)

the Supreme Court visited the issue of whether an "alert" by drug detection dog could provide probable cause to search a vehicle. In this case, Aldo, a German Shepherd, "alerted" to the driver's door handle of a truck that his handler had stopped for an equipment violation. A subsequent search of the truck produced evidence of methamphetamine manufacturing.

In Aguilar v. Texas (1964)

the court devised a two-pronged test. The first prong tested the informant's credibility. Is the person reliable? Is the informant's identity known? Is the informant a law-abiding citizen or a criminal? The second prong tested the informant's basis of knowledge and reliability of the information provided. Is the information accurate? Did the informant personally witness the information given? If not, did the information come from another source? Is the information still believable? What is this informant's track record?

Probable cause exist when

the facts and circumstances within the officers' knowledge and of which they had reasonable trustworthy information are sufficient in themselves to warrant a person of reasonable caution in the belief that an offense has been or is being committed.

knock-and-announce rule

the intent of which is to protect human life, prevent the unnecessary destruction of property, and to protect a person's privacy and dignity when faced with a sudden police entrance (Hudson v. Michigan, 2006).

In Hudson v. Michigan (2006) the Court specifically ruled that violation of the knock-and-announce rule does not require suppression of the evidence obtained during the ensuing search. In other words, the general rule excluding evidence obtained in violation of the Fourth Amendment does not apply to

the knock-and-announce rule. In this case, the Court did refer to alternative remedies such as civil lawsuits or internal discipline but held that the exclusionary rule was too high a social cost for this violation.

Totality of circumstances is

the principle upon which a number of legal assessments are made, including probable cause.

Observing furtive conduct, that is, questionable, suspicious, or secretive behavior, will understandably raise an officer's suspicion, and although a person's level of nervousness may not be enough by itself, it can play a part in

the totality of the circumstances

In determining whether probable cause for the warrant exists, the reviewing judge must consider

the totality of the circumstances. In other words, all the factors submitted are viewed as a whole in considering whether a reasonable person would believe what the officers claim. The warrant must include the reasons for requesting it, the names of the officers who applied for it, names of others who have information to contribute, what or who specifically is being sought, and the signature of the judge issuing it.

Stop-and-frisk law

to balance the rights of an individual and the government's need for tools to carry out its job of protecting society from lawbreakers. Police officers should neither be expected to ignore their reasonable suspicions nor be denied the right to ensure their own safety by checking for weapons.

Facts and evidence obtained after a search or arrest can not be used to establish probable cause. They can be used to

to strengthen the case if probable cause was established before the arrest, making the arrest legal.

The Constitution doesn't provide an absolute right to be free from government intrusion, only

unreasonable interference.

the fourth amendment prohibits

unreasonable searches and seizures

False or implausible answers may also contribute to probable cause, such as occurred in United States v. Anderson (1987),

when officers stopped a car on a road known to be used by people transporting drugs and found a large amount of cash wrapped in small bundles, secured with rubber bands. The suspects said they had just won the money in Atlantic City, but the officers did not believe the answers fit their questions.

Illinois v. Gates

which sharpened up the definition of what constitutes probable cause and the totality of the circumstances to be considered. In this case, a tip from an anonymous informant led to police obtaining and executing a search warrant for drugs in the defendant's home. Justice William Rehnquist held that because "the most basic function of any government is to provide for the security of the individual and of his property," the spirit of the law was better served by determination of the existence of probable cause by consideration of the totality of the circumstances in deciding whether a "reasonable and prudent person" would believe that, in this case, contraband was located in a particular location, thus, indicating criminal activity. Justice Rehnquist noted that "probable cause is a fluid concept—turning on the assessment of probabilities in a particular factual context—not readily, or even usefully reduced to a neat set of legal rules." This totality of circumstances test made establishment of probable cause by use of informants easier for police.