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The Fourth Amendment (Amendment IV) to the
United States Constitution The Constitution of the United States is the supreme law of the United States of America. It superseded the Articles of Confederation, the nation's first constitution, in 1789. Originally comprising seven articles, it delineates the natio ...
is part of the
Bill of Rights A bill of rights, sometimes called a declaration of rights or a charter of rights, is a list of the most important rights to the citizens of a country. The purpose is to protect those rights against infringement from public officials and pr ...
. It prohibits unreasonable
searches and seizures Search and seizure is a procedure used in many civil law and common law legal systems by which police or other authorities and their agents, who, suspecting that a crime has been committed, commence a search of a person's property and confis ...
. In addition, it sets requirements for issuing
warrants Warrant may refer to: * Warrant (law), a form of specific authorization ** Arrest warrant, authorizing the arrest and detention of an individual ** Search warrant, a court order issued that authorizes law enforcement to conduct a search for eviden ...
: warrants must be issued by a judge or magistrate, justified by
probable cause In United States criminal law, probable cause is the standard by which police authorities have reason to obtain a warrant for the arrest of a suspected criminal or the issuing of a search warrant. There is no universally accepted definition o ...
, supported by oath or affirmation, and must particularly describe the place to be searched and the persons or things to be seized. Fourth Amendment case law deals with three main issues: what government activities are "searches" and "seizures," what constitutes probable cause to conduct searches and seizures, and how to address violations of Fourth Amendment rights. Early court decisions limited the amendment's scope to physical intrusion of property or persons, but with ''
Katz v. United States ''Katz v. United States'', 389 U.S. 347 (1967), was a landmark decision of the U.S. Supreme Court in which the Court redefined what constitutes a "search" or "seizure" with regard to the protections of the Fourth Amendment to the U.S. Constituti ...
'' (1967), the
Supreme Court A supreme court is the highest court within the hierarchy of courts in most legal jurisdictions. Other descriptions for such courts include court of last resort, apex court, and high (or final) court of appeal. Broadly speaking, the decisions of ...
held that its protections extend to intrusions on the privacy of individuals as well as to physical locations. A warrant is needed for most search and seizure activities, but the Court has carved out a series of exceptions for
consent search Consent searches (or consensual searches) are searches made by police officers in the United States based on the voluntary consent of the individual whose person or property is being searched. The simplest and most common type of warrantless sear ...
es, motor vehicle searches, evidence in plain view,
exigent circumstances In criminal procedure law of the United States, an exigent circumstance allows law enforcement (under certain circumstances) to enter a structure without a search warrant, or if they have a " knock and announce" warrant, allows them to enter without ...
, border searches, and other situations. The
exclusionary rule In the United States, the exclusionary rule is a legal rule, based on constitutional law, that prevents evidence collected or analyzed in violation of the defendant's constitutional rights from being used in a court of law. This may be consider ...
is one way the amendment is enforced. Established in ''
Weeks v. United States ''Weeks v. United States'', 232 U.S. 383 (1914), was a United States Supreme Court case in which the Court unanimously held that the warrantless seizure of items from a private residence constitutes a violation of the Fourth Amendment to the U.S ...
'' (1914), this rule holds that
evidence Evidence for a proposition is what supports this proposition. It is usually understood as an indication that the supported proposition is true. What role evidence plays and how it is conceived varies from field to field. In epistemology, evidenc ...
obtained as a result of a Fourth Amendment violation is generally inadmissible at criminal trials. Evidence discovered as a later result of an illegal search may also be inadmissible as "
fruit of the poisonous tree Fruit of the poisonous tree is a legal metaphor used to describe evidence that is obtained illegally. The logic of the terminology is that if the source (the "tree") of the evidence or evidence itself is tainted, then anything gained (the "fruit") ...
." The exception is if it inevitably would have been discovered by legal means. The Fourth Amendment was introduced in Congress in 1789 by
James Madison James Madison Jr. (March 16, 1751June 28, 1836) was an American statesman, diplomat, and Founding Father. He served as the fourth president of the United States from 1809 to 1817. Madison is hailed as the "Father of the Constitution" for h ...
, along with the other amendments in the Bill of Rights, in response to
Anti-Federalist Anti-Federalism was a late-18th century political movement that opposed the creation of a stronger U.S. federal government and which later opposed the ratification of the 1787 Constitution. The previous constitution, called the Articles of Conf ...
objections to the new Constitution. Congress submitted the amendment to the states on September 28, 1789. By December 15, 1791, the necessary three-fourths of the states had
ratified Ratification is a principal's approval of an act of its agent that lacked the authority to bind the principal legally. Ratification defines the international act in which a state indicates its consent to be bound to a treaty if the parties inten ...
it. On March 1, 1792, Secretary of State
Thomas Jefferson Thomas Jefferson (April 13, 1743 – July 4, 1826) was an American statesman, diplomat, lawyer, architect, philosopher, and Founding Fathers of the United States, Founding Father who served as the third president of the United States from 18 ...
announced that it was officially part of the Constitution. Because the Bill of Rights did not initially apply to state or local governments, and federal criminal investigations were less common in the first century of the nation's history, there is little significant case law for the Fourth Amendment before the 20th century. The amendment was held to apply to state and local governments in '' Mapp v. Ohio'' (1961) via the
Due Process Clause In United States constitutional law, a Due Process Clause is found in both the Fifth and Fourteenth Amendments to the United States Constitution, which prohibits arbitrary deprivation of "life, liberty, or property" by the government except a ...
of the Fourteenth Amendment.


Text


Background


English law

Like many other areas of American law, the Fourth Amendment finds its origin in English legal doctrine. In ''
Semayne's case ''Semayne's Case'' (January 1, 1604) 5 Coke Rep. 91, is an English common law case reported by Sir Edward Coke, who was then the Attorney General of England. In the United States, it is recognized as establishing the "knock-and-announce" rule. ...
'' (1604),
Sir Edward Coke ''Sir'' is a formal honorific address in English for men, derived from Sire in the High Middle Ages. Both are derived from the old French "Sieur" (Lord), brought to England by the French-speaking Normans, and which now exist in French only as ...
famously stated: "The house of every one is to him as his castle and fortress, as well for his defence against injury and violence as for his repose." ''Semayne's Case'' acknowledged that the King did not have unbridled authority to intrude on his subjects' dwellings, but recognized that government agents were permitted to conduct searches and seizures under certain conditions when their purpose was lawful and a warrant had been obtained. The 1760s saw a growth in the intensity of litigation against state officers, who using general warrants, conducted raids in search of materials relating to
John Wilkes John Wilkes (17 October 1725 – 26 December 1797) was an English radical journalist and politician, as well as a magistrate, essayist and soldier. He was first elected a Member of Parliament in 1757. In the Middlesex election dispute, he ...
's publications. The most famous of these cases involved
John Entick John Entick (c.1703 – May 1773) was an English schoolmaster and author. He was largely a hack writer, working for Edward Dilly, and he padded his credentials with a bogus M.A. and a portrait in clerical dress; some of his works had a more l ...
whose home was forcibly entered by the
King's Messenger The Corps of King's Messengers (or Corps of Queen's Messengers during the reign of a female monarch) are couriers employed by the British Foreign, Commonwealth and Development Office (FCDO). They hand-carry secret and important documents to B ...
Nathan Carrington, along with others, pursuant to a warrant issued by
George Montagu-Dunk, 2nd Earl of Halifax George Montagu-Dunk, 2nd Earl of Halifax, (6 October 1716 – 8 June 1771) was a British statesman of the Georgian era. Due to his success in extending commerce in the Americas, he became known as the "father of the colonies". President of the ...
authorizing them "to make strict and diligent search for ... the author, or one concerned in the writing of several weekly very seditious papers entitled, ' The Monitor or British Freeholder, No 257, 357, 358, 360, 373, 376, 378, and 380'", the search resulting in seizure of printed charts, pamphlets and other materials. Entick filed suit in '' Entick v Carrington'', argued before the Court of King's Bench in 1765.
Charles Pratt, 1st Earl Camden Charles Pratt, 1st Earl Camden, PC (baptised 21 March 1714 – 18 April 1794) was an English lawyer, judge and Whig politician who was first to hold the title of Earl Camden. As a lawyer and judge he was a leading proponent of civil liberti ...
ruled that both the search and the seizure were unlawful, as the warrant authorized the seizure of ''all'' of Entick's papers—not just the criminal ones—and as the warrant lacked
probable cause In United States criminal law, probable cause is the standard by which police authorities have reason to obtain a warrant for the arrest of a suspected criminal or the issuing of a search warrant. There is no universally accepted definition o ...
to even justify the search. By holding that " r law holds the property of every man so sacred, that no man can set his foot upon his neighbour's close without his leave", ''Entick'' established the English precedent that the executive is limited in intruding on private property by
common law In law, common law (also known as judicial precedent, judge-made law, or case law) is the body of law created by judges and similar quasi-judicial tribunals by virtue of being stated in written opinions."The common law is not a brooding omniprese ...
.


Colonial America

Homes in
Colonial America The colonial history of the United States covers the history of European colonization of North America from the early 17th century until the incorporation of the Thirteen Colonies into the United States after the Revolutionary War. In the ...
, on the other hand, did not enjoy the same sanctity as their British counterparts, because legislation had been explicitly written so as to enable enforcement of British revenue-gathering policies on customs; until 1750, in fact, the only type of warrant defined in the handbooks for justices of the peace was the general warrant. During what scholar William Cuddihy called the "colonial epidemic of general searches", the authorities possessed almost unlimited power to search for anything at any time, with very little oversight. In 1756, the colony of Massachusetts barred the use of general warrants. This represented the first law in American history curtailing the use of seizure power. Its creation largely stemmed from the great public outcry over the Excise Act of 1754, which gave tax collectors unlimited powers to interrogate colonists concerning their use of goods subject to customs. The act also permitted the use of a general warrant known as a writ of assistance, allowing tax collectors to search the homes of colonists and seize "prohibited and uncustomed" goods. A crisis erupted over the writs of assistance on December 27, 1760, when the news of King George II's death on October 23 arrived in Boston. All writs automatically expired six months after the death of the King, and would have had to be re-issued by
George III George III (George William Frederick; 4 June 173829 January 1820) was King of Great Britain and of Ireland from 25 October 1760 until the union of the two kingdoms on 1 January 1801, after which he was King of the United Kingdom of Great Br ...
, the new king, to remain valid. In mid-January 1761, a group of more than fifty merchants represented by James Otis petitioned the court to have hearings on the issue. During the five-hour hearing on February 23, 1761, Otis vehemently denounced British colonial policies, including their sanction of general warrants and writs of assistance. However, the court ruled against Otis. Future President
John Adams John Adams (October 30, 1735 – July 4, 1826) was an American statesman, attorney, diplomat, writer, and Founding Fathers of the United States, Founding Father who served as the second president of the United States from 1797 to 1801. Befor ...
, who was present in the courtroom when Otis spoke, viewed these events as "the spark in which originated the American Revolution". Because of the name he had made for himself in attacking the writs, Otis was elected to the Massachusetts colonial legislature and helped pass legislation requiring that special writs of assistance be "granted by any judge or justice of the peace upon information under oath by any officer of the customs" and barring all other writs. The governor overturned the legislation, finding it contrary to English law and parliamentary sovereignty. Seeing the danger general warrants presented, the
Virginia Declaration of Rights The Virginia Declaration of Rights was drafted in 1776 to proclaim the inherent rights of men, including the right to reform or abolish "inadequate" government. It influenced a number of later documents, including the United States Declaratio ...
(1776) explicitly forbade the use of general warrants. This prohibition became a precedent for the Fourth Amendment: Article XIV of the Massachusetts Declaration of Rights, written by
John Adams John Adams (October 30, 1735 – July 4, 1826) was an American statesman, attorney, diplomat, writer, and Founding Fathers of the United States, Founding Father who served as the second president of the United States from 1797 to 1801. Befor ...
and enacted in 1780 as part of the Massachusetts Constitution, added the requirement that all searches must be "reasonable", and served as another basis for the language of the Fourth Amendment: By 1784, eight state constitutions contained a provision against general warrants.


Proposal and ratification

After several years of comparatively weak government under the
Articles of Confederation The Articles of Confederation and Perpetual Union was an agreement among the 13 Colonies of the United States of America that served as its first frame of government. It was approved after much debate (between July 1776 and November 1777) by ...
, a Constitutional Convention in Philadelphia proposed a new constitution on September 17, 1787, featuring a stronger chief executive and other changes.
George Mason George Mason (October 7, 1792) was an American planter, politician, Founding Father, and delegate to the U.S. Constitutional Convention of 1787, one of the three delegates present who refused to sign the Constitution. His writings, including ...
, a Constitutional Convention delegate and the drafter of Virginia's Declaration of Rights, proposed that a bill of rights listing and guaranteeing
civil liberties Civil liberties are guarantees and freedoms that governments commit not to abridge, either by constitution, legislation, or judicial interpretation, without due process. Though the scope of the term differs between countries, civil liberties ma ...
be included. Other delegates—including future Bill of Rights drafter
James Madison James Madison Jr. (March 16, 1751June 28, 1836) was an American statesman, diplomat, and Founding Father. He served as the fourth president of the United States from 1809 to 1817. Madison is hailed as the "Father of the Constitution" for h ...
—disagreed, arguing that existing state guarantees of civil liberties were sufficient and that any attempt to enumerate individual rights risked implying that other, unnamed rights were unprotected. After a brief debate, Mason's proposal was defeated by a unanimous vote of the state delegations. For the Constitution to be ratified, nine of the thirteen states were required to approve it in state conventions. Opposition to ratification ("Anti-Federalism") was partly based on the Constitution's lack of adequate guarantees for civil liberties. Supporters of the Constitution in states where popular sentiment was against ratification (including Virginia, Massachusetts, and New York) successfully proposed that their state conventions both ratify the Constitution and call for the addition of a bill of rights. Four state conventions proposed some form of restriction on the authority of the new federal government to conduct searches. In the
1st United States Congress The 1st United States Congress, comprising the United States Senate and the United States House of Representatives, met from March 4, 1789, to March 4, 1791, during the first two years of George Washington's presidency, first at Federal Hall i ...
, following the state legislatures' request, James Madison proposed twenty constitutional amendments based on state bills of rights and English sources such as the
Bill of Rights 1689 The Bill of Rights 1689 is an Act of the Parliament of England, which sets out certain basic civil rights and clarifies who would be next to inherit the Crown, and is seen as a crucial landmark in English constitutional law. It received Royal ...
, including an amendment requiring probable cause for government searches. Congress reduced Madison's proposed twenty amendments to twelve, with modifications to Madison's language about searches and seizures. The final language was submitted to the states for ratification on September 25, 1789. By the time the Bill of Rights was submitted to the states for ratification, opinions had shifted in both parties. Many Federalists, who had previously opposed a Bill of Rights, now supported the Bill as a means of silencing the Anti-Federalists' most effective criticism. Many Anti-Federalists, in contrast, now opposed it, realizing the Bill's adoption would greatly lessen the chances of a second constitutional convention, which they desired. Anti-Federalists such as
Richard Henry Lee Richard Henry Lee (January 20, 1732June 19, 1794) was an American statesman and Founding Father from Virginia, best known for the June 1776 Lee Resolution, the motion in the Second Continental Congress calling for the colonies' independence f ...
also argued that the Bill left the most objectionable portions of the Constitution, such as the federal judiciary and direct taxation, intact. On November 20, 1789, New Jersey ratified eleven of the twelve amendments, including the Fourth. On December 19, 1789, December 22, 1789, and January 19, 1790, respectively, Maryland, North Carolina, and South Carolina ratified all twelve amendments. On January 25 and 28, 1790, respectively, New Hampshire and Delaware ratified eleven of the Bill's twelve amendments, including the Fourth. This brought the total of ratifying states to six of the required ten, but the process stalled in other states: Connecticut and Georgia found a Bill of Rights unnecessary and so refused to ratify, while Massachusetts ratified most of the amendments, but failed to send official notice to the Secretary of State that it had done so (all three states would later ratify the Bill of Rights for sesquicentennial celebrations in 1939). In February through June 1790, New York, Pennsylvania, and Rhode Island each ratified eleven of the amendments, including the Fourth. Virginia initially postponed its debate, but after Vermont was admitted to the Union in 1791, the total number of states needed for ratification rose to eleven. Vermont ratified on November 3, 1791, approving all twelve amendments, and Virginia finally followed on December 15, 1791. Secretary of State
Thomas Jefferson Thomas Jefferson (April 13, 1743 – July 4, 1826) was an American statesman, diplomat, lawyer, architect, philosopher, and Founding Fathers of the United States, Founding Father who served as the third president of the United States from 18 ...
announced the adoption of the ten successfully ratified amendments on March 1, 1792.


Applicability

The Fourth Amendment, and the personal rights which it secures, have a long history. The Bill of Rights originally restricted only the
federal government A federation (also known as a federal state) is a political entity characterized by a union of partially self-governing provinces, states, or other regions under a central federal government ( federalism). In a federation, the self-gover ...
, and went through a long initial phase of "judicial dormancy;" in the words of historian
Gordon S. Wood Gordon Stewart Wood (born November 27, 1933) is an American historian and professor at Brown University. He is a recipient of the 1993 Pulitzer Prize for History for '' The Radicalism of the American Revolution'' (1992). His book ''The Creation o ...
, "After ratification, most Americans promptly forgot about the first ten amendments to the Constitution." Federal jurisdiction regarding criminal law was narrow until the late 19th century when the Interstate Commerce Act and
Sherman Antitrust Act The Sherman Antitrust Act of 1890 (, ) is a United States antitrust law which prescribes the rule of free competition among those engaged in commerce. It was passed by Congress and is named for Senator John Sherman, its principal author. ...
were passed. As federal criminal jurisdiction expanded to include other areas such as
narcotic The term narcotic (, from ancient Greek ναρκῶ ''narkō'', "to make numb") originally referred medically to any psychoactive compound with numbing or paralyzing properties. In the United States, it has since become associated with opiates ...
s, more questions about the Fourth Amendment came to the U.S. Supreme Court. The Supreme Court responded to these questions by stating on the one hand that the government powers to search and seizure are limited by the Fourth Amendment so that arbitrary and oppressive interference by enforcement officials with the privacy and personal security of individuals are prevented and by outlining on the other hand the fundamental purpose of the amendment as guaranteeing "the privacy, dignity and security of persons against certain arbitrary and invasive acts by officers of the Government, without regard to whether the government actor is investigating crime or performing another function".'' Ontario v. Quon'', 130 S.Ct. 2619, . To protect personal privacy and dignity against unwarranted intrusion by the State is the overriding function of the Fourth Amendment according to the Court in '' Schmerber v. California'' (1966), because " e security of one's privacy against arbitrary intrusion by the police" is "at the core of the Fourth Amendment" and "basic to a free society." Pointing to historic precedents like '' Entick v Carrington'' (1765) and '' Boyd v. United States'' (1886), the Supreme Court held in '' Silverman v. United States'' (1961) that the Fourth Amendments core is the right to retreat into his own home and there be free from unreasonable governmental intrusion. With a view to '' Camara v. Municipal Court'' (1967) the Supreme Court observed in ''
Torres v. Madrid ''Torres v. Madrid'', 592 U.S. ___ (2021), was a United States Supreme Court case based on what constitutes a "seizure" in the context of the Fourth Amendment to the United States Constitution, in the immediate case, in the situation where law en ...
'' (2021) that the focus of the Fourth Amendment is the privacy and security of individuals, not the particular manner of arbitrary invasion by governmental officials. In '' Mapp v. Ohio'' (1961),'' Mapp v. Ohio'', . the Supreme Court ruled that the Fourth Amendment applies to the states by way of the
Due Process Clause In United States constitutional law, a Due Process Clause is found in both the Fifth and Fourteenth Amendments to the United States Constitution, which prohibits arbitrary deprivation of "life, liberty, or property" by the government except a ...
of the Fourteenth Amendment. Fourth Amendment case law deals with three central issues: what government activities constitute "search" and "seizure;" what constitutes
probable cause In United States criminal law, probable cause is the standard by which police authorities have reason to obtain a warrant for the arrest of a suspected criminal or the issuing of a search warrant. There is no universally accepted definition o ...
for these actions; how violations of Fourth Amendment rights should be addressed. "The Fourth Amendment search and seizure doctrine involves a complex compromise between public safety and the constitutional right to personal liberty." The Fourth Amendment typically requires "a neutral and detached authority interposed between the police and the public", and it is offended by "general warrants" and laws that allow searches to be conducted "indiscriminately and without regard to their connection with crime under investigation", for the "basic purpose of the Fourth Amendment, which is enforceable against the States through the Fourteenth, through its prohibition of 'unreasonable' searches and seizures is to safeguard the privacy and security of individuals against arbitrary invasions by governmental officials." The Fourth Amendment has been held to mean that a search or an arrest generally requires a judicially sanctioned warrant, because the basic rule under the Fourth Amendment is that arrests and "searches conducted outside the judicial process, without prior approval by judge or magistrate, are ''per se'' unreasonable". In order for such a warrant to be considered reasonable, it must be supported by probable cause and be limited in scope according to specific information supplied by a person (usually a law enforcement officer) who has sworn by it and is therefore accountable to the issuing court. The Supreme Court further held in ''
Chandler v. Miller ''Chandler v. Miller'', 520 U.S. 305 (1997), was a case before the United States Supreme Court concerning the Constitutionality under the Fourth Amendment of a state statute requiring drug tests of all candidates for certain state offices. The c ...
'' (1997): "To be reasonable under the Fourth Amendment, a search ordinarily must be based on individualized suspicion of wrongdoing. But particularized exceptions to the main rule are sometimes warranted based on 'special needs, beyond the normal need for law enforcement'. ... When such 'special needs' are alleged, courts must undertake a context-specific inquiry, examining closely the competing private and public interests advanced by the parties." The amendment applies to governmental searches and seizures, but not those done by private citizens or organizations who are not acting on behalf of a government. In '' Ontario v. Quon'' (2010), the Court applied the amendment to a municipal government in its capacity as an employer, ruling that the City of Ontario had not violated the Fourth Amendment rights of city police officers by obtaining from the communications company and reviewing transcripts of text messages sent using government-provided pagers.


Search

One threshold question in the Fourth Amendment jurisprudence is whether a "search" has occurred. Initial Fourth Amendment case law hinged on a citizen's
property rights The right to property, or the right to own property (cf. ownership) is often classified as a human right for natural persons regarding their possessions. A general recognition of a right to private property is found more rarely and is typically h ...
—that is, when the government physically intrudes on "persons, houses, papers, or effects" for the purpose of obtaining information, a "search" within the original meaning of the Fourth Amendment has occurred. Early 20th-century Court decisions, such as '' Olmstead v. United States'' (1928), held that Fourth Amendment rights applied in cases of physical intrusion, but not to other forms of police surveillance (e.g., wiretaps). In '' Silverman v. United States'' (1961), the Court stated of the amendment that "at the very core stands the right of a man to retreat into his own home and there be free from unreasonable governmental intrusion". Fourth Amendment protections expanded significantly with ''
Katz v. United States ''Katz v. United States'', 389 U.S. 347 (1967), was a landmark decision of the U.S. Supreme Court in which the Court redefined what constitutes a "search" or "seizure" with regard to the protections of the Fourth Amendment to the U.S. Constituti ...
'' (1967). In ''Katz'', the Supreme Court expanded that focus to embrace an individual's
right to privacy The right to privacy is an element of various legal traditions that intends to restrain governmental and private actions that threaten the privacy of individuals. Over 150 national constitutions mention the right to privacy. On 10 December 194 ...
, and ruled that a search had occurred when the government wiretapped a
telephone booth A telephone booth, telephone kiosk, telephone call box, telephone box or public call box is a tiny structure furnished with a payphone and designed for a telephone user's convenience; usually the user steps into the booth and closes the booth ...
using a microphone attached to the outside of the glass. While there was no physical intrusion into the booth, the Court reasoned that: 1) Katz, by entering the booth and shutting the door behind him, had exhibited his expectation that "the words he utters into the mouthpiece will not be broadcast to the world"; and 2) society believes that his expectation was reasonable. Justice
Potter Stewart Potter Stewart (January 23, 1915 – December 7, 1985) was an American lawyer and judge who served as an Associate Justice of the United States Supreme Court from 1958 to 1981. During his tenure, he made major contributions to, among other areas ...
wrote in the majority opinion that "the Fourth Amendment protects people, not places". A "search" occurs for purposes of the Fourth Amendment when the government violates a person's "reasonable expectation of privacy". Katz's reasonable
expectation of privacy Expectation of privacy is a legal test which is crucial in defining the scope of the applicability of the privacy protections of the Fourth Amendment to the United States Constitution. It is related to, but is not the same as, a ''right to privac ...
thus provided the basis to rule that the government's intrusion, though electronic rather than physical, was a search covered by the Fourth Amendment, and thus necessitated a warrant. The Court said it was not recognizing any general right to privacy in the Fourth Amendment, and that this wiretap could have been authorized if proper procedures had been followed. This decision in ''Katz'' was later developed into the now commonly used two-prong test, adopted in ''
Smith v. Maryland ''Smith v. Maryland'', 442 U.S. 735 (1979), was a Supreme Court case holding that the installation and use of a pen register by the police to obtain information on a suspect's telephone calls was not a "search" within the meaning of the Fourth Ame ...
'' (1979),''
Smith v. Maryland ''Smith v. Maryland'', 442 U.S. 735 (1979), was a Supreme Court case holding that the installation and use of a pen register by the police to obtain information on a suspect's telephone calls was not a "search" within the meaning of the Fourth Ame ...
'', .
for determining whether a search has occurred for purposes of the Fourth Amendment: # a person "has exhibited an actual (subjective) expectation of privacy"; and # society is prepared to recognize that this expectation is (objectively) reasonable. The Supreme Court has held that the Fourth Amendment does not apply to information that is voluntarily shared with third parties. In ''Smith'', the Court held individuals have no "legitimate expectation of privacy" regarding the telephone numbers they dial because they knowingly give that information to telephone companies when they dial a number. However, under '' Carpenter v. United States'' (2018), individuals have a reasonable expectation of privacy under the Fourth Amendment regarding cell phone records even though they themselves turned over that information to "third parties" (i.e. the cell phone companies). Prior to the Carpenter ruling, law enforcement was able to retrieve cell site location information (CSLI) that included where a cell phone user had traveled over many months and with which other cell phone users they had associated. Carpenter v. United States serves as a landmark case because it slightly narrowed the Third Party Doctrine, thus requiring law enforcement to first obtain a search warrant before receiving CSLI records. "In the 5-4 arpenterdecision, the Court ruled 'narrowly' in favor of privacy, finding the government had constitutionally violated Mr. Carpenter's reasonable expectation of privacy by acquiring this private information without a warrant." Following ''Katz'', the vast majority of Fourth Amendment search cases have turned on the right to privacy, but in '' United States v. Jones'' (2012), the Court ruled that the ''Katz'' standard did not replace earlier case law, but rather, has supplemented it.'' United States v. Jones'', . In ''Jones'', law enforcement officers had attached a GPS device on a car's exterior without Jones' knowledge or consent. The Court concluded that Jones was a
bailee Bailment is a legal relationship in common law, where the owner transfers physical possession of personal property ("chattel") for a time, but retains ownership. The owner who surrenders custody to a property is called the "bailor" and the in ...
to the car, and so had a property interest in the car. Therefore, since the intrusion on the vehicle—a common law
trespass Trespass is an area of tort law broadly divided into three groups: trespass to the person, trespass to chattels, and trespass to land. Trespass to the person historically involved six separate trespasses: threats, assault, battery, woundi ...
—was for the purpose of obtaining information, the Court ruled that it was a search under the Fourth Amendment. The Court used similar "trespass" reasoning in ''
Florida v. Jardines ''Florida v. Jardines'', 569 U.S. 1 (2013), was a United States Supreme Court case which resulted in the decision that police use of a trained detection dog to sniff for narcotics on the front porch of a private home is a "search" within the meani ...
'' (2013), to rule that bringing a drug
detection dog A detection dog or sniffer dog is a dog that is trained to use its senses to detect substances such as explosives, illegal drugs, wildlife scat, currency, blood, and contraband electronics such as illicit mobile phones. The sense most used ...
to sniff at the front door of a home was a search.''
Florida v. Jardines ''Florida v. Jardines'', 569 U.S. 1 (2013), was a United States Supreme Court case which resulted in the decision that police use of a trained detection dog to sniff for narcotics on the front porch of a private home is a "search" within the meani ...
'', .
In certain situations, law enforcement may perform a search when they have a reasonable suspicion of criminal activity, even if it falls short of probable cause necessary for an arrest. Under '' Terry v. Ohio'' (1968), law enforcement officers are permitted to conduct a limited warrantless search on a level of suspicion less than probable cause under certain circumstances. In ''Terry'', the Supreme Court ruled that when a police officer witnesses "unusual conduct" that leads the officer to reasonably believe "that criminal activity may be afoot", that the suspicious person has a weapon ''and'' that the person is presently dangerous to the officer or others, the officer may conduct a pat-down search ("frisk" the person) to determine whether the person is carrying a weapon. This detention and search is known as a ''Terry'' stop. To conduct a frisk, officers must be able to point to specific and articulable facts which, taken together with rational inferences from those facts, reasonably warrant their actions. As established in ''
Florida v. Royer ''Florida v. Royer'', 460 U.S. 491 (1983), was a U.S. Supreme Court case dealing with issues involving the Fourth Amendment. Specifically, the case establishes a firm line in cases where police conduct search and seizure without a warrant. The ...
'' (1983), such a search must be temporary, and questioning must be limited to the purpose of the stop (e.g., officers who stop a person because they have reasonable suspicion to believe the person was driving a stolen car, cannot, after confirming it is not stolen, compel the person to answer questions about anything else, such as contraband).''
Florida v. Royer ''Florida v. Royer'', 460 U.S. 491 (1983), was a U.S. Supreme Court case dealing with issues involving the Fourth Amendment. Specifically, the case establishes a firm line in cases where police conduct search and seizure without a warrant. The ...
'', .


Seizure

The Fourth Amendment proscribes unreasonable seizure of any person, person's home (including its
curtilage In common law, the curtilage of a house or dwelling is the land immediately surrounding it, including any closely associated buildings and structures, but excluding any associated " open fields beyond". In feudal times every castle with its depen ...
) or
personal property property is property that is movable. In common law systems, personal property may also be called chattels or personalty. In civil law systems, personal property is often called movable property or movables—any property that can be moved fr ...
without a warrant. A seizure of property occurs when there is "some meaningful interference with an individual's possessory interests in that property," such as when police officers take personal property away from an owner to use as evidence, or when they participate in an eviction. The amendment also protects against unreasonable seizure of persons, including a brief detention. A seizure does not occur just because the government questions an individual in a public place. The exclusionary rule would not bar voluntary answers to such questions from being offered into evidence in a subsequent criminal prosecution. The person is not being seized if his freedom of movement is not restrained. The government may not detain an individual even momentarily without reasonable, objective grounds, with few exceptions. His refusal to listen or answer does not by itself furnish such grounds. In '' United States v. Mendenhall'' (1980), the Court held that a person is seized only when, by means of physical force ''or'' show of authority, his freedom of movement is restrained and, in the circumstances surrounding the incident, a reasonable person would believe he was not free to leave.'' United States v. Mendenhall'', . Under ''
Torres v. Madrid ''Torres v. Madrid'', 592 U.S. ___ (2021), was a United States Supreme Court case based on what constitutes a "seizure" in the context of the Fourth Amendment to the United States Constitution, in the immediate case, in the situation where law en ...
'' (2021), a person is considered to be seized following the use of physical force with the intent to restrain, even if the person manages to escape. In '' Florida v. Bostick'' (1991), the Court ruled that as long as the police do not convey a message that compliance with their requests is required, the police contact is a "citizen encounter" that falls outside the protections of the Fourth Amendment. If a person remains free to disregard questioning by the government, there has been no seizure and therefore no intrusion upon the person's privacy under the Fourth Amendment. When a person is arrested and taken into police custody, he has been seized (i.e., a reasonable person who is handcuffed and placed in the back of a police car would not think they were free to leave). A person subjected to a routine
traffic stop A traffic stop, commonly referred to as being pulled over, is a temporary detention of a driver of a vehicle by police to investigate a possible crime or minor violation of law. United States A traffic stop is usually considered to be a ...
on the other hand, has been seized, but is not "arrested" because traffic stops are a relatively brief encounter and are more analogous to a ''Terry'' stop than to a formal arrest.''
Knowles v. Iowa ''Knowles v. Iowa'', 525 U.S. 113 (1998), was a decision by the United States Supreme Court which ruled that the Fourth Amendment prohibits a police officer from further searching a vehicle which was stopped for a minor traffic offense once the of ...
'', .
If a person is not under suspicion of illegal behavior, a law enforcement official is not allowed to place an individual under arrest simply because this person does not wish to state his identity, provided specific state regulations do not specify this to be the case. A search incidental to an arrest that is not permissible under state law does not violate the Fourth Amendment, so long as the arresting officer has probable cause. In ''
Maryland v. King In ''Maryland v. King'', 569 U.S. 435 (2013), the United States Supreme Court decided that a cheek swab of an arrestee's DNA is comparable to fingerprinting and therefore, a legal police booking procedure that is reasonable under the Fourth Ame ...
'' (2013), the Court upheld the constitutionality of police swabbing for DNA upon arrests for serious crimes, along the same reasoning that allows police to take fingerprints or photographs of those they arrest and detain.


Exceptions

The government may not detain an individual even momentarily without reasonable and articulable suspicion, with a few exceptions. In '' Delaware v. Prouse'' (1979), the Court ruled an officer has made an illegal seizure when he stops an automobile and detains the driver in order to check his driver's license and the registration of the automobile, because the officer does not have articulable and reasonable suspicion that a motorist is unlicensed or that an automobile is not registered, or either the vehicle or an occupant is otherwise subject to seizure for violation of law. Where society's need is great, no other effective means of meeting the need is available, and intrusion on people's privacy is minimal, certain discretionless checkpoints toward that end may briefly detain motorists. In '' United States v. Martinez-Fuerte'' (1976), the Supreme Court allowed discretionless immigration checkpoints. In '' Michigan Dept. of State Police v. Sitz'' (1990), the Supreme Court allowed discretionless sobriety checkpoints. In ''
Illinois v. Lidster ''Illinois v. Lidster'', 540 U.S. 419 (2004), was a case in which the Supreme Court of the United States ruled that the Fourth Amendment to the United States Constitution, Fourth Amendment permits the police to use a roadblock to investigate a traf ...
'' (2004), the Supreme Court allowed focused informational checkpoints. However, in '' City of Indianapolis v. Edmond'' (2000), the Supreme Court ruled that discretionary checkpoints or general crime-fighting checkpoints are not allowed.


Warrant

Under the Fourth Amendment, law enforcement must receive written permission from a court of law, or otherwise qualified
magistrate The term magistrate is used in a variety of systems of governments and laws to refer to a civilian officer who administers the law. In ancient Rome, a '' magistratus'' was one of the highest ranking government officers, and possessed both judic ...
, to lawfully search and seize evidence while investigating criminal activity. A court grants permission by issuing a
writ In common law, a writ (Anglo-Saxon ''gewrit'', Latin ''breve'') is a formal written order issued by a body with administrative or judicial jurisdiction; in modern usage, this body is generally a court. Warrants, prerogative writs, subpoenas, a ...
known as a warrant. A search or seizure is generally unreasonable and unconstitutional if conducted without a valid warrant and the police must obtain a warrant whenever practicable. Searches and seizures without a warrant are not considered unreasonable if one of the specifically established and well-delineated exceptions to the warrant requirement applies.''
New Jersey v. T. L. O. ''New Jersey v. T.L.O.'', 469 U.S. 325 (1985), is a landmark decision of the Supreme Court of the United States which established the standards by which a public school official can search a student in a school environment, and to what extent. The ...
'', '. " rrantless searches are per se unreasonable, subject only to a few specifically delineated and well-recognized exceptions. ... full-scale searches—whether conducted in accordance with the warrant requirement or pursuant to one of its exceptions—are 'reasonable' in Fourth Amendment terms only on a showing of probable cause to believe that a crime has been committed and that evidence of the crime will be found in the place to be searched."
These exceptions apply " ly in those exceptional circumstances in which special needs, beyond the normal need for law enforcement, make the warrant and probable cause requirement impracticable." In these situations where the warrant requirement doesn't apply a search or seizure nonetheless must be justified by some individualized suspicion of wrongdoing. However, the U.S. Supreme Court carved out an exception to the requirement of individualized suspicion. It ruled that, "In limited circumstances, where the privacy interests implicated by the search are minimal and where an important governmental interest furthered by the intrusion would be placed in jeopardy by a requirement of individualized suspicion" a search r seizurewould still be reasonable.


Probable cause

The standards of probable cause differ for an arrest and a search. The government has probable cause to make an arrest when "the facts and circumstances within their knowledge and of which they had reasonably trustworthy information" would lead a prudent person to believe the arrested person had committed or was committing a crime. Probable cause to arrest must exist before the arrest is made. Evidence obtained after the arrest may not apply retroactively to justify the arrest. When police conduct a search, the amendment requires that the warrant establish probable cause to believe the search will uncover criminal activity or contraband. They must have legally sufficient reasons to believe a search is necessary. In '' Carroll v. United States'' (1925), the Supreme Court stated that probable cause to search is a flexible, common-sense standard.'' Carroll v. United States'', . To that end, the Court ruled in '' Dumbra v. United States'' (1925) that the term probable cause means "less than evidence that would justify condemnation," reiterating ''Carroll''s assertion that it merely requires that the facts available to the officer would "warrant a man of reasonable caution" in the belief that specific items may be contraband or stolen property or useful as evidence of a crime. It does not demand any showing that such a belief be correct or more likely true than false. A "practical, non-technical" probability that incriminating evidence is involved is all that is required. In ''
Illinois v. Gates ''Illinois v. Gates'', 462 U.S. 213 (1983), is a Fourth Amendment case. ''Gates'' overruled ''Aguilar v. Texas'' and '' Spinelli v. United States'', thereby replacing the Aguilar–Spinelli test for probable cause with the "totality of the circum ...
'' (1983), the Court ruled that the reliability of an informant is to be determined based on the " totality of the circumstances."


Exceptions to the warrant requirement


Consent

If a
party A party is a gathering of people who have been invited by a host for the purposes of socializing, conversation, recreation, or as part of a festival or other commemoration or celebration of a special occasion. A party will often featu ...
gives consent to a search, a warrant is not required. There are exceptions and complications to the rule, including the scope of the consent given, whether the consent is voluntarily given, and whether an individual has the right to consent to a search of another's property. In '' Schneckloth v. Bustamonte'' (1973), the Court ruled that a consent search is still valid even if the police do not inform a suspect of his right to refuse the search. This contrasts with Fifth Amendment rights, which cannot be relinquished without an explicit ''Miranda'' warning from police. The Court stated in '' United States v. Matlock'' (1974) that a third party co-occupant could give consent for a search without violating a suspect's Fourth Amendment rights. However, in '' Georgia v. Randolph'' (2006), the Supreme Court ruled that when two co-occupants are both present, one consenting and the other rejecting the search of a shared residence, the police may not make a search of that residence within the consent exception to the warrant requirement. Per the Court's ruling in '' Illinois v. Rodriguez'' (1990), a consent search is still considered valid if police accept in good faith the consent of an "apparent authority," even if that party is later discovered to not have authority over the property in question. A telling case on this subject is ''Stoner v. California'', in which the Court held that police officers could not rely in good faith upon the apparent authority of a hotel clerk to consent to the search of a guest's room.


Plain view and open fields

According to the plain view doctrine as defined in '' Coolidge v. New Hampshire'' (1971), if an officer is lawfully present, he may seize objects that are in "plain view." However, the officer must have had probable cause to believe the objects are contraband. What's more, the criminality of the object in plain view must be obvious by its very nature. In ''
Arizona v. Hicks ''Arizona v. Hicks'', 480 U.S. 321 (1987), held that the Fourth Amendment to the United States Constitution, Fourth Amendment requires the police to have probable cause to seize items in plain view. Facts On April 20, 1984, a bullet was fired thro ...
'', the Supreme Court held that an officer stepped beyond the plain view doctrine when he moved a turntable in order to view its serial number to confirm that the turntable was stolen. "A search is a search," proclaimed the Court, "even if it happens to disclose nothing but the bottom of a turntable." Similarly, "open fields" such as pastures, open water, and woods may be searched without a warrant, on the ground that conduct occurring therein would have no reasonable expectation of privacy. The doctrine was first articulated by the Court in ''
Hester v. United States ''Hester v. United States'', 265 U.S. 57 (1924), is a decision by the United States Supreme Court, which established the open-fields doctrine. In an opinion written by Justice Oliver Wendell Holmes, Jr., Oliver Wendell Holmes, the Court held that " ...
'' (1924), which stated that "the special protection accorded by the Fourth Amendment to the people in their 'persons, houses, papers, and effects' is not extended to the open fields." In ''
Oliver v. United States ''Oliver v. United States'', 466 U.S. 170 (1984), is a United States Supreme Court decision relating to the open fields doctrine limiting the Fourth Amendment to the United States Constitution. Background Acting upon a tip that defendant was grow ...
'' (1984), the police ignored a "no trespassing" sign and a fence, trespassed onto the suspect's land without a warrant, followed a path for hundreds of feet, and discovered a field of marijuana. The Supreme Court ruled that no search had taken place, because there was no privacy expectation regarding an open field: While open fields are not protected by the Fourth Amendment, the
curtilage In common law, the curtilage of a house or dwelling is the land immediately surrounding it, including any closely associated buildings and structures, but excluding any associated " open fields beyond". In feudal times every castle with its depen ...
, or outdoor area immediately surrounding the home, is protected. Courts have treated this area as an extension of the house and as such subject to all the privacy protections afforded a person's home (unlike a person's open fields) under the Fourth Amendment. The curtilage is "intimately linked to the home, both physically and psychologically", and is where "privacy expectations are most heightened." However, courts have held aerial surveillance of curtilage not to be included in the protections from unwarranted search so long as the airspace above the curtilage is generally accessible by the public. An area is curtilage if it "harbors the intimate activity associated with the sanctity of a man's home and the privacies of life." Courts make this determination by examining "whether the area is included within an enclosure surrounding the home, the nature of the uses to which the area is put, and the steps taken by the resident to protect the area from observation by people passing by." The Court has acknowledged that a doorbell or knocker is typically treated as an invitation, or license, to the public to approach the front door of the home to deliver mail, sell goods, solicit for charities, etc. This license extends to the police, who have the right to try engaging a home's occupant in a "
knock and talk In law enforcement, a knock and talk is an investigative technique where one or more police officers approaches a private residence, knocks on the door, and requests consent from the owner to search the residence. This strategy is often utilised wh ...
" for the purpose of gathering evidence without a warrant. However, they cannot bring a drug detection dog to sniff at the front door of a home without either a warrant or consent of the homeowner or resident.


Exigent circumstance

Law enforcement officers may also conduct warrantless searches in several types of exigent circumstances where obtaining a warrant is dangerous or impractical. Under '' Terry v. Ohio'' (1968) police are permitted to frisk suspects for weapons. The Court also allowed a search of arrested persons in ''Weeks v. United States'' (1914) to preserve evidence that might otherwise be destroyed and to ensure suspects were disarmed. In ''Carroll v. United States'' (1925), the Court ruled that law enforcement officers could search a vehicle that they suspected of carrying contraband without a warrant. The Court allowed blood to be drawn without a warrant from drunk-driving suspects in '' Schmerber v. California'' (1966) on the grounds that the time to obtain a warrant would allow a suspect's
blood alcohol content Blood alcohol content (BAC), also called blood alcohol concentration or blood alcohol level, is a measurement of alcohol intoxication used for legal or medical purposes; it is expressed as mass of alcohol per volume or mass of blood. For example ...
to reduce, although this was later modified by ''
Missouri v. McNeely ''Missouri v. McNeely'', 569 U.S. 141 (2013), was a case decided by United States Supreme Court, on appeal from the Supreme Court of Missouri, regarding exceptions to the Fourth Amendment to the United States Constitution under exigent circumstan ...
'' (2013). '' Warden v. Hayden'' (1967) provided an exception to the warrant requirement if officers were in "hot pursuit" of a suspect. A subset of exigent circumstances is the debated community caretaking exception.


Motor vehicle

The Supreme Court has held that individuals in automobiles have a reduced expectation of privacy, because (1) vehicles generally do not serve as residences or repositories of personal effects, and (2) vehicles "can be quickly moved out of the locality or jurisdiction in which the warrant must be sought." Vehicles may not be randomly stopped and searched; there must be probable cause or reasonable suspicion of criminal activity. Items in plain view may be seized; areas that could potentially hide weapons may also be searched. With probable cause to believe evidence is present, police officers may search any area in the vehicle. However, they may not extend the search to the vehicle's passengers without probable cause to search those passengers or consent from the passengers. In ''
Collins v. Virginia ''Collins v. Virginia'', No. 16-1027, 584 U.S. ___ (2018), was a case before the US Supreme Court involving search and seizure. At issue was whether the Fourth Amendment's motor vehicle exception permits a police officer uninvited and without a w ...
'' (2018), the Court ruled that the motor vehicle exception did not apply to searches of vehicles parked within a residence's
curtilage In common law, the curtilage of a house or dwelling is the land immediately surrounding it, including any closely associated buildings and structures, but excluding any associated " open fields beyond". In feudal times every castle with its depen ...
. In ''
Arizona v. Gant ''Arizona v. Gant'', 556 U.S. 332 (2009), was a United States Supreme Court decision holding that the Fourth Amendment to the United States Constitution requires law enforcement officers to demonstrate an actual and continuing threat to their safet ...
'' (2009), the Court ruled that a law enforcement officer needs a warrant before searching a motor vehicle after an arrest of an occupant of that vehicle, unless 1) at the time of the search the person being arrested is unsecured and within reaching distance of the passenger compartment of the vehicle or 2) police officers have reason to believe evidence for the crime for which the person is being arrested will be found in the vehicle.


Searches incident to a lawful arrest

A
common law In law, common law (also known as judicial precedent, judge-made law, or case law) is the body of law created by judges and similar quasi-judicial tribunals by virtue of being stated in written opinions."The common law is not a brooding omniprese ...
rule from Great Britain permits searches incident to an arrest without a warrant. This rule has been applied in American law, and has a lengthy common law history. The justification for such a search is to prevent the arrested individual 1.) from destroying evidence or 2.) using a weapon against the arresting officer by disarming the suspect. The U.S. Supreme Court ruled that "both justifications for the search-incident-to-arrest exception are absent and the rule does not apply" when "there is no possibility" the suspect could gain access to a weapon or destroy evidence. In '' Trupiano v. United States'' (1948), the Supreme Court held that "a search or seizure without a warrant as an incident to a lawful arrest has always been considered to be a strictly limited right. It grows out of the inherent necessities of the situation at the time of the arrest. But there must be something more in the way of necessity than merely a lawful arrest." In '' United States v. Rabinowitz'' (1950), the Court reversed ''Trupiano'', holding instead that the officers' opportunity to obtain a warrant was not germane to the reasonableness of a search incident to an arrest. ''Rabinowitz'' suggested that any area within the "immediate control" of the arrestee could be searched, but it did not define the term. In deciding '' Chimel v. California'' (1969), the Supreme Court elucidated its previous decisions. It held that when an arrest is made, it is reasonable for the officer to search the arrestee for weapons and evidence. However, in ''
Riley v. California ''Riley v. California'', 573 U.S. 373 (2014),''Riley v. California''573 U.S. 373(2014). is a landmark United States Supreme Court case in which the court ruled that the warrantless search and seizure of the digital contents of a cell phone during ...
'' (2014), the Supreme Court ruled unanimously that police must obtain a warrant to search an arrestee's cellular phone. The Court said that earlier Supreme Court decisions permitting searches incident to an arrest without a warrant do not apply to "modern cellphones, which are now such a pervasive and insistent part of daily life that the proverbial visitor from Mars might conclude they were an important feature of human anatomy," and noted that U.S. citizens' cellphones today typically contain "a digital record of nearly every aspect of their lives—from the mundane to the intimate."


Border search exception

Searches conducted at the United States border or the equivalent of the border (such as an international airport) may be conducted without a warrant or probable cause subject to the border search exception. Most border searches may be conducted entirely at random, without any level of suspicion, pursuant to U.S. Customs and Border Protection plenary search authority. However, searches that intrude upon a traveler's personal dignity and privacy interests, such as strip and body cavity searches, must be supported by "reasonable suspicion". The U.S. Courts of Appeals for the Fourth and
Ninth In music, a ninth is a compound interval consisting of an octave plus a second. Like the second, the interval of a ninth is classified as a dissonance in common practice tonality. Since a ninth is an octave larger than a second, its ...
circuits have ruled that information on a traveler's electronic materials, including personal files on a laptop computer, may be searched at random, without suspicion.


Foreign intelligence surveillance

The Supreme Court decision in '' United States v. U.S. District Court'' (1972) left open the possibility for a foreign intelligence surveillance exception to the warrant clause. Three United States Courts of Appeals have recognized a foreign intelligence surveillance exception to the warrant clause, but tied it to certain requirements. The exception to the Fourth Amendment was formally recognized by the United States Foreign Intelligence Surveillance Court of Review in its 2008 '' In re Directives'' decision. The lower court held that "a foreign intelligence exception to the Fourth Amendment's warrant requirement exists when surveillance is conducted to obtain foreign intelligence for national security purposes and is directed against foreign powers or agents of foreign powers reasonably believed to be located outside the United States." Despite the foregoing citation the Fourth Amendment prohibitions against unreasonable searches and seizures nonetheless apply to the contents of all communications, whatever the means, because, "a person's private communications are akin to personal papers." Fourth Amendment reasonableness is the point at which the United States government's interest advanced by a particular search or seizure outweighs the loss of individual privacy or freedom of movement that attends the government's action. The United Supreme Court said in '' Board of Education v. Earls'' (2002) when 'special needs', beyond the normal need for law enforcement, make the warrant and probable-cause requirement impracticable the reasonableness of a search is determined by balancing the nature of the intrusion on the individual's privacy against the promotion of legitimate governmental interests. Additionally in ''
Illinois v. Lidster ''Illinois v. Lidster'', 540 U.S. 419 (2004), was a case in which the Supreme Court of the United States ruled that the Fourth Amendment to the United States Constitution, Fourth Amendment permits the police to use a roadblock to investigate a traf ...
'' (2004) the Court explained in judging reasonableness it looks to "the gravity of the public concerns served by the seizure, the degree to which the seizure advances the public interest, and the severity of the interference with individual liberty". To protect the
telecommunication Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that ...
carriers cooperating with the U.S. government from legal action, the Congress passed a bill updating the
Foreign Intelligence Surveillance Act The Foreign Intelligence Surveillance Act of 1978 ("FISA" , ) is a United States federal law that establishes procedures for the physical and electronic surveillance and the collection of "foreign intelligence information" between "foreign pow ...
of 1978 to permit this type of surveillance.


Schools and prisons

In ''
New Jersey v. T. L. O. ''New Jersey v. T.L.O.'', 469 U.S. 325 (1985), is a landmark decision of the Supreme Court of the United States which established the standards by which a public school official can search a student in a school environment, and to what extent. The ...
'' (1985), the Supreme Court ruled that searches in public schools do not require warrants, as long as the searching officers have reasonable grounds for believing the search will result in finding evidence of illegal activity. Similarly, in '' Samson v. California'' (2006), the Court ruled that government offices may be searched for evidence of work-related misconduct by government employees on similar grounds. Searches of prison cells are subject to no restraints relating to reasonableness or probable cause. However, in ''
Safford Unified School District v. Redding ''Safford Unified School District v. Redding'', 557 U.S. 364 (2009), was a case in which the Supreme Court of the United States held that a strip search of a middle school student by school officials violated the Fourth Amendment to the U.S. Co ...
'' (2009), the Court ruled that school officials violated the Fourth Amendment when they strip searched a student based only on another student's claiming to have received drugs from her.


Exclusionary rule

One way courts enforce the Fourth Amendment is through the use of the exclusionary rule. The rule provides that evidence obtained through a violation of the Fourth Amendment is generally not admissible by the prosecution during the defendant's criminal trial. The Court stated in ''
Elkins v. United States ''Elkins v. United States'', 364 U.S. 206 (1960), was a US Supreme Court decision that held the "silver platter doctrine", which allowed federal prosecutors to use evidence illegally gathered by state police, to be a violation of the Fourth Amen ...
'' (1960) that the rule's function "is to deter—to compel respect for the constitutional guaranty in the only effectively available way—by removing the incentive to disregard it." The Court adopted the exclusionary rule in ''
Weeks v. United States ''Weeks v. United States'', 232 U.S. 383 (1914), was a United States Supreme Court case in which the Court unanimously held that the warrantless seizure of items from a private residence constitutes a violation of the Fourth Amendment to the U.S ...
'' (1914),''
Weeks v. United States ''Weeks v. United States'', 232 U.S. 383 (1914), was a United States Supreme Court case in which the Court unanimously held that the warrantless seizure of items from a private residence constitutes a violation of the Fourth Amendment to the U.S ...
'', .
prior to which all evidence, no matter how seized, could be admitted in court. In '' Silverthorne Lumber Co. v. United States'' (1920) and '' Nardone v. United States'' (1939), the Court ruled that leads or other evidence resulting from illegally obtained evidence are also inadmissible in trials. Justice
Felix Frankfurter Felix Frankfurter (November 15, 1882 – February 22, 1965) was an Austrian-American jurist who served as an Associate Justice of the Supreme Court of the United States from 1939 until 1962, during which period he was a noted advocate of judic ...
described this secondary evidence in the ''Nardone'' decision as the "
fruit of the poisonous tree Fruit of the poisonous tree is a legal metaphor used to describe evidence that is obtained illegally. The logic of the terminology is that if the source (the "tree") of the evidence or evidence itself is tainted, then anything gained (the "fruit") ...
". The Supreme Court rejected incorporating the exclusionary rule by way of the Fourteenth Amendment in '' Wolf v. Colorado'' (1949), but ''Wolf'' was explicitly overruled in ''Mapp v. Ohio'' (1961), making the Fourth Amendment (including the exclusionary rule) applicable in state proceedings. The exclusionary rule and its effectiveness have often been controversial, particularly since its 1961 application to state proceedings. Critics charge that the rule hampers police investigation and can result in freeing guilty parties convicted on reliable evidence; other critics say the rule has not been successful in deterring illegal police searches. Proponents argue that the number of criminal convictions overturned under the rule has been minimal and that no other effective mechanism exists to enforce the Fourth Amendment. In 1982,
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
passed a " Victim's Bill of Rights" containing a provision to repeal the exclusionary rule; though the bill could not affect federally mandated rights under the Fourth Amendment, it blocked the state courts from expanding these protections further.


Limitations

Since 1974, the Supreme Court has repeatedly limited the exclusionary rule. In '' United States v. Calandra'' (1974), the Court ruled that
grand juries A grand jury is a jury—a group of citizens—empowered by law to conduct legal proceedings, investigate potential criminal conduct, and determine whether criminal charges should be brought. A grand jury may subpoena physical evidence or a per ...
may use illegally obtained evidence when questioning witnesses, because "the damage to that institution from the unprecedented extension of the exclusionary rule outweighs the benefit of any possible incremental deterrent effect." Explaining the purpose of the rule, the Court said the rule "is a judicially created remedy designed to safeguard Fourth Amendment rights generally through its deterrent effect, rather than a personal constitutional right of the party aggrieved." Three cases in 1984 further restricted the exclusionary rule: * In ''
United States v. Leon ''United States v. Leon'', 468 U.S. 897 (1984), was a United States Supreme Court case in which the Court established the "good faith" exception to the Fourth Amendment exclusionary rule.. Background In August 1981, police in Burbank, California ...
'' (1984), the Court established the "good faith" exception to the rule, ruling that evidence seized by officers reasonably relying on a warrant was still admissible, even though the warrant was later found to be defective, unless an officer dishonestly or recklessly prepared an affidavit to seek a warrant, the issuing magistrate abandoned his neutrality, or the warrant lacked sufficient particularity. * The Court determined in '' Nix v. Williams'' (1984) that "fruit of the poisonous tree" evidence could still be introduced if a prosecutor could demonstrate that it would have been an "inevitable discovery" of legitimate investigation. * In '' Segura v. United States'' (1984), the Court ruled that evidence illegally found without a search warrant is admissible if the evidence is later found and legally seized based on information independent of the illegal search. In '' Arizona v. Evans'' (1995) and ''
Herring v. United States ''Herring v. United States'', 555 U.S. 135 (2009), was a case decided by the Supreme Court of the United States on January 14, 2009. The court decided that the good-faith exception to the exclusionary rule applies when a police officer makes an a ...
'' (2009), the Court ruled that the exclusionary rule does not apply to evidence found due to negligence regarding a government database, as long as the arresting police officer relied on that database in "good faith" and the negligence was not pervasive. In '' Davis v. United States'' (2011), the Court ruled that the exclusionary rule does not apply to a Fourth Amendment violation resulting from a reasonable reliance on binding appellate precedent. In '' Utah v. Strieff'' (2016), the Court ruled that evidence obtained from an unlawful police stop would not be excluded from court when the link between the stop and the evidence's discovery was "attenuated" by the discovery of an outstanding warrant during the stop. The Supreme Court has also held the exclusionary rule to not apply in the following circumstances: * evidence illegally seized by a "private actor" (i.e., not a governmental employee) * tax hearings * evidence collected by U.S. Customs agents * deportation hearings * evidence seized by probation or parole officers * probation or parole revocation hearings


Metadata

On December 16, 2013, in ''
Klayman v. Obama ''Klayman v. Obama'', 957 F.Supp.2d 1 (D.D.C., 2013), was a decision by the United States District Court for the District of Columbia, United States District Court for District of Columbia finding that the National Security Agency's (NSA) bulk ...
'', a
United States district court The United States district courts are the trial courts of the U.S. federal judiciary. There is one district court for each federal judicial district, which each cover one U.S. state or, in some cases, a portion of a state. Each district co ...
ruled that the mass collection of
metadata Metadata is "data that provides information about other data", but not the content of the data, such as the text of a message or the image itself. There are many distinct types of metadata, including: * Descriptive metadata – the descriptive ...
of Americans' telephone records by the National Security Agency probably violates the Fourth Amendment. The court granted a preliminary injunction, blocking the collection of phone data for two private plaintiffs and ordered the government to destroy any of their records that have been gathered. The court stayed the ruling pending a government appeal, recognizing the "significant national security interests at stake in this case and the novelty of the constitutional issues." However, in '' ACLU v. Clapper'', a United States district court ruled that the U.S. government's global telephone data-gathering system is needed to thwart potential terrorist attacks, and that it can work only if everyone's calls are included. The court also ruled that Congress legally set up the program and it does not violate anyone's constitutional rights. The court concluded that the telephone data being swept up by NSA did not belong to telephone users, but to the telephone companies. Also, the court held that when NSA obtains such data from the telephone companies, and then probes into it to find links between callers and potential terrorists, this further use of the data was not even a search under the Fourth Amendment, concluding that the controlling precedent is ''
Smith v. Maryland ''Smith v. Maryland'', 442 U.S. 735 (1979), was a Supreme Court case holding that the installation and use of a pen register by the police to obtain information on a suspect's telephone calls was not a "search" within the meaning of the Fourth Ame ...
'', saying "Smith's bedrock holding is that an individual has no legitimate expectation of privacy in information provided to third parties." The
American Civil Liberties Union The American Civil Liberties Union (ACLU) is a nonprofit organization founded in 1920 "to defend and preserve the individual rights and liberties guaranteed to every person in this country by the Constitution and laws of the United States". T ...
declared on January 2, 2014, that it will appeal the ruling that NSA bulk phone record collection is legal. "The government has a legitimate interest in tracking the associations of suspected terrorists, but tracking those associations does not require the government to subject every citizen to permanent surveillance," deputy ACLU legal director Jameel Jaffer said in a statement.


See also

*
Article 8 of the European Convention on Human Rights Article 8 of the European Convention on Human Rights provides a right to respect for one's "private and family life, his home and his correspondence", subject to certain restrictions that are "in accordance with law" and " necessary in a democrati ...
*
Fourth Amendment Protection Act The Fourth Amendment to the United States Constitution, Fourth Amendment Protection Acts, are a collection of state legislation aimed at withdrawing state support for bulk data (metadata) collection and ban the use of warrant-less data in state cour ...
* NSA warrantless surveillance (2001–07)#Fourth Amendment issues * Parallel construction * Privacy laws of the United States *
Special needs exception The "special needs" exception is an exception to the Fourth Amendment’s general requirement that government searches be supported by a warrant and probable cause. The exception applies when (1) the government conducts programmatic searches tha ...
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Section Eight of the Canadian Charter of Rights and Freedoms Section 8 of the ''Canadian Charter of Rights and Freedoms'' protects against unreasonable search and seizure. This right provides those in Canada with their primary source of constitutionally enforced privacy rights against unreasonable intrusion ...
* '' subpoena ad testificandum'' * ''
subpoena duces tecum A ''subpoena duces tecum'' (pronounced in English ), or subpoena for production of evidence, is a court summons ordering the recipient to appear before the court and produce documents or other tangible evidence for use at a hearing or trial. In s ...
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Notes

Citations


References

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External links


CRS Annotated Constitution: Fourth Amendment
Cornell University Cornell University is a private statutory land-grant research university based in Ithaca, New York. It is a member of the Ivy League. Founded in 1865 by Ezra Cornell and Andrew Dickson White, Cornell was founded with the intention to tea ...
{{Authority control 1791 in American law 1791 in American politics 04 Government documents of the United States Police legislation + Searches and seizures United States criminal constitutional law