The Fourth Amendment (Amendment IV) to the United States Constitution is a part of the Bill of Rights. The Fourth Amendment guards against unreasonable searches and seizures, and was designed as a response to the controversial writ of assistance (a type of general search warrant), which was a significant factor behind the American Revolution. Toward that end, the amendment specifies that judicially sanctioned search and arrest warrants 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.
In Mapp v. Ohio, , the Supreme Court ruled that the Fourth Amendment is applicable to the state governments by way of the Due Process Clause of the Fourteenth Amendment. The Supreme Court has said that some searches and seizures may violate the Fourth Amendment's reasonableness requirement even when a warrant is permissibly granted.
As with many other forms of American law, the Fourth Amendment finds its roots in English legal doctrine, and first identified by Edward Coke in Semayne's case in which he articulated that:
The case acknowledged that the King did not have unbridled authority to intrude on his subject's dwelling but recognized that, when the appropriate agents were employed, their purpose was lawful and a warrant was obtained, government agents were permitted to conduct searches and seizures. The following years 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' publications attacking both government policies and the King himself. The most famous of these cases involved John Entick, whose home was forcibly entered by the King's Messenger Nathan Carrington, along with others, pursuant to a warrant issued by George Montagu-Dunk, 2nd Earl of Halifax authorizing them “to make strict and diligent search for . . . the author, or one concerned in the writing of several weekly very seditious papers intitled, ‘The Monitor or British Freeholder, No 357, 358, 360, 373, 376, 378, and 380,’″ and seized printed charts, pamphlets and other materials. In the resulting case, Entick v. Carrington, Charles Pratt, 1st Earl Camden ruled that the search and seizure was unlawful as the warrant authorized the seizure of all of Entick's papers, not just the criminal ones and the warrant lacked probable cause to even justify the search. Entick established the English precedent that the executive is limited in intruding on private property by common law.
In 1756, the province of Massachusetts enacted legislation that 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 and permitted the use of a general warrant known as a writ of assistance, allowing them 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 October 23 death arrived in Boston. All writs automatically expired six months after the death of the King and would have had to be re-issued under the name of the new King, George III, in order to remain valid.
In mid-January 1761, a group of over 50 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 English colonial policies, including their sanction of general warrants and writs of assistance. However, the court ruled against Otis. Because of the name he had made for himself in attacking the writs, he was elected to the Massachusetts General Assembly 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 British law and parliamentary sovereignty. John Adams, who was present in the courtroom when Otis spoke, viewed these events “as the spark in which originated the American Revolution.”
Seeing the danger general warrants presented, the Virginia Declaration of Rights explicitly forbid the use of general warrants. This prohibition became precedent for the Fourth Amendment:
The Fourth Amendment only applies to governmental actors. It does not guarantee a right to be free from unreasonable searches and seizures conducted by private citizens or organizations. The Bill of Rights originally only restricted the power of the federal government, but the Supreme Court of the United States has ruled that the Fourth Amendment is applicable to state governments by way of the Due Process Clause of the Fourteenth Amendment. Moreover, all state constitutions contain an analogous provision.
The Fourth Amendment applies to criminal law, but not civil law. This was affirmed by the Supreme Court in 1855, in the Murray v. Hoboken Land decision. The jurisdiction of the federal government in the realm of criminal law was narrow, up until the late 19th century when the Interstate Commerce Act and Sherman Antitrust Act were passed. As criminal jurisdiction of the federal government expanded to include other areas such as narcotics, more questions about the Fourth Amendment came to the Supreme Court.
The Supreme Court has said that some searches and seizures may violate the Fourth Amendment's reasonableness requirement even if a warrant is supported by probable cause and is limited in scope. Conversely, the Court has approved routine warrantless seizures, for example "where there is probable cause to believe that a criminal offense has been or is being committed. Thus, the reasonableness requirement and the warrant requirement are somewhat different.
Regarding the Fourth Amendment's reasonableness requirement, it applies not just to a search in combination with a seizure, but also applies to a search without a seizure, as well as to a seizure without a search. Hence, the amendment is not limited to protecting elements of privacy or personal autonomy, but rather applies pervasively to virtually all aspects of criminal law. Nevertheless, the amendment is not so broad as to replace other constitutional provisions, such as replacing the Eighth Amendment's ban on "cruel and unusual" punishment with a more sweeping ban on "unreasonable" punishment.
A seizure is not constituted by merely approaching the individual on the street or in another public place, and asking him if he is willing to answer some questions, or by asking him questions if he seems willing to listen, or by offering in evidence in a criminal prosecution his voluntary answers to such questions. The person approached, however, does not have to answer any questions under these circumstances; he can simply walk away. He may not be detained even momentarily without reasonable, objective grounds for doing so; and his refusal to listen or answer does not, without more, furnish those grounds.
A person is seized within the meaning of the Fourth Amendment 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 that he was not free to leave. If the police are questioning someone, and they remain free to disregard the questions and walk away, there has been no intrusion upon the person's liberty or privacy, and for Fourth Amendment purposes — there has been no seizure.
The probable cause required for an arrest is different than that required for a search. Police have 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 that the arrested person had committed or was committing a crime. Probable cause to arrest must exist before the arrest is made: evidence discovered after the arrest may not be retroactively used to justify the arrest.
The Court adopted the exclusionary rule in Weeks v. United States, , prior to which all evidence, no matter how seized, could be admitted in court. Additionally, in Silverthorne Lumber Co. v. United States, and Nardone v. United States, , the Court ruled that tips resulting from illegally obtained evidence are also inadmissible in trials as fruit of the poisonous tree. The rule serves primarily to deter police officers from willfully violating a suspect's Fourth Amendment rights. The rationale behind the exclusionary rule is that if the police know evidence obtained in violation of the Fourth Amendment cannot be used to convict someone of a crime, they will not violate it. In delivering the opinion of the Court, Justice Frankfurter, in Wolf v. Colorado, , rejected incorporation of the Fourth Amendment by way of the Fourteenth Amendment. Later, in Mapp v. Ohio, , the Supreme Court explicitly overruled Wolf and made the Fourth Amendment (including the exclusionary rule) applicable in state proceedings as an essential part of criminal procedure.
The Supreme Court has held the rule does not apply in certain situations: (1) probation or parole revocation hearings; (2) tax hearings; (3) deportation hearings; (4) when government officials illegally seize evidence outside the United States; (5) when a "private actor" (i.e., not a governmental employee) illegally seized the evidence; or (6) when the illegally seized evidence is used to impeach the defendant's testimony. Furthermore, a defendant has standing to object to the admission of unconstitutionally seized evidence only if such seizure violated his own Fourth Amendment rights; a defendant may not assert the rights of a third party. For example, a mere passenger in a car has standing to contest the stop of the car and a search of his person, but he usually lacks standing to contest a search of the car. If he is a passenger in his own car, however, he would have standing to challenge the search of the car.
The open fields doctrine was first articulated by the Supreme Court in Hester v. United States, , 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." This opinion appears to be decided on the basis that "open fields are not a 'constitutionally protected area' because they cannot be construed as "persons, houses, papers, [or] effects."
This method of reasoning gave way with the arrival of the landmark case Katz v. United States, , which established a two-part test for what constitutes a search within the meaning of the Fourth Amendment. The relevant criteria are "first that a person have exhibited an actual (subjective) expectation of privacy and, second, that the expectation be one that society is prepared to recognize as reasonable." Under this “new” analysis of the Fourth Amendment, privacy expectations deemed unreasonable by society cannot be validated by any steps taken by the defendant to shield the area from view.
In Oliver v. United States, , the police ignored a "no trespassing" sign, trespassed onto the suspect's land without a warrant, followed a path several hundred yards, 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:
…open fields do not provide the setting for those intimate activities that the Amendment is intended to shelter from government interference or surveillance. There is no societal interest in protecting the privacy of those activities, such as the cultivation of crops, that occur in open fields.
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. Theoretically, many structures might extend the curtilage protection to the areas immediately surrounding them. The courts have gone so far as to treat a tent as a home for Fourth Amendment purposes in the past. It is possible that the area immediately surrounding a tent (or any structure used as a home) might be considered curtilage.
Despite this rather broad interpretation of curtilage, the courts seem willing to find areas to be outside of the curtilage if they are in any way separate from the home (by a fence, great distance, other structures, even certain plants).
Similarly, it was held that it is reasonable for the officer to search the area within the arrestee's immediate control, that is, the area from which the defendant may gain access to a weapon or evidence. A search of the room in which the arrest is made is therefore permissible, but the same is not true of a search of other rooms, as the arrestee would not probably be able to access weapons or evidence in those rooms at the time of arrest.
Similarly, Samson v. California, held 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 or searches undertaken as a condition of parole.
Finally, a search is reasonable if the target without coercion consents to the search, even if the target is unaware and not told about their right to refuse to cooperate.
In a memo dated March 14, 2003, an official in the Bush administration stated "... our Office recently concluded that the Fourth Amendment had no application to domestic military operations". The administration believed that any search or surveillance conducted by the National Security Agency of US citizens communicating with foreign nationals abroad was immune to a Fourth Amendment challenge. To protect the telecommunication carriers cooperating with the US government from legal action, the Congress passed a bill updating the Foreign Intelligence Surveillance Act of 1978 to permit this type of surveillance.
Many cases discuss whether a private employee (i.e., not a government employee) who stores incriminating evidence in workplace computers is protected by the Fourth Amendment's reasonable expectation of privacy standard in a criminal proceeding. However, these cases do not appear to produce a uniform and consistent standard of law. Most case law holds that employees do not have a reasonable expectation of privacy when it comes to their work related electronic communications. However, one federal court held that employees can assert the attorney-client privilege with respect to certain communications on company laptops.
On January 30, 2007, the Ninth Circuit court in United States v. Ziegler, reversed its earlier August 2006 decision upon a petition for rehearing. In contrast to the earlier decision, the Court acknowledged that an employee has a right to privacy in his workplace computer. However, the Court also found that an employer can consent to any illegal searches and seizures. In Ziegler, an employee had accessed child pornography websites from his workplace. His employer noticed his activities, made copies of the hard drive, and gave the FBI the employee's computer. At his criminal trial, Ziegler filed a motion to suppress the evidence because he argued that the government violated his Fourth Amendment rights. The Ninth Circuit allowed the lower court to admit the child pornography evidence. After reviewing relevant Supreme Court opinions on a reasonable expectation of privacy, the Court acknowledged that Ziegler had a reasonable expectation of privacy at his office and on his computer. That Court also found that his employer could consent to a government search of the computer, and that did not violate Ziegler's Fourth Amendment rights. In 2008, the New Jersey Supreme Court held that computer users can expect that the personal information they give their internet service providers is considered private. In that case, prosecutors asserted that Shirley Reid broke into her employer’s computer system and changed its shipping address and password for suppliers. The police discovered her identity after getting a subpoena to the internet provider, Comcast Internet Service. The lower court suppressed information from the internet service provider that linked Reid with the crime and the New Jersey Superior Court agreed with that decision. Although this case does not directly discuss the Fourth Amendment, it illustrates that some states are providing more privacy protection to computer users than is provided by the federal courts. It also illustrates that case law on privacy in workplace computers is still evolving.
Arrest and Search of a Person Without a Warrant
Search of and Seizure from a Residence Without a Warrant
Search and Seizure of Vehicles and Containers Without a Warrant
Plain-view & Plain-feel
Stop and Frisk