
The Fourth Amendment to the United States Constitution, part of the Bill of Rights, was ratified on December 15, 1791. It protects the American people from unreasonable searches and seizures, and sets requirements for issuing warrants. The amendment was introduced by James Madison and underwent modest changes in Congress. The Fourth Amendment has been frequently debated in recent years, as police and intelligence agencies in the United States have engaged in controversial activities, including the bulk collection of telephone and internet data, and aggressive stop and frisk practices. The amendment has been invoked in numerous landmark cases, including Carpenter v. United States, which narrowed the Third Party Doctrine and required law enforcement to obtain a search warrant before accessing cell site location information.
| Characteristics | Values |
|---|---|
| Date of Ratification | December 15, 1791 |
| Prohibits | Unreasonable searches and seizures |
| Requirements for issuing warrants | Warrants must be issued by a judge or magistrate, justified by probable cause, supported by oath or affirmation, and must particularly describe the place to be searched and the persons or things to be seized |
| 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 |
| Notable Cases | Carpenter v. United States, Klayman v. Obama, Katz v. United States, Silverthorne Lumber Co. v. United States, Nardone v. United States, Wilkes v. Wood, Entick v. Carrington, Riley v. California |
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What You'll Learn

The right to privacy
The Fourth Amendment to the United States Constitution is part of the Bill of Rights and deals with the right to privacy. It was created in response to increasing infringements on privacy in the colonies and in England. In England, “general warrants” allowed royal officials to search the belongings of any individual suspected of being a political enemy. In the colonies, "writs of assistance" authorised officials to conduct warrantless searches for untaxed items.
The Fourth Amendment prohibits unreasonable searches and seizures and sets requirements for issuing warrants. Warrants must be issued by a judge or magistrate, justified by probable cause, supported by oath or affirmation, and must specifically describe the place to be searched and the persons or things to be seized.
The amendment has been interpreted and contested in various court cases. In Carpenter v. United States, the Supreme Court ruled that law enforcement must obtain a search warrant before accessing cell site location information (CSLI) records, thus narrowing the Third-Party Doctrine and upholding the right to privacy. Similarly, in Klayman v. Obama, a district court ruled that the National Security Agency's mass collection of Americans' telephone records likely violated the Fourth Amendment, recognising the importance of protecting individuals' privacy.
However, in the name of national security and crime prevention, there have been instances of widespread surveillance and data collection by government agencies. Critics argue that these programs are invasive and violate the Fourth Amendment. Supporters, on the other hand, justify them based on "probable cause".
While the Fourth Amendment protects against unreasonable searches and seizures, it does not guarantee protection from all searches and seizures. Courts require claimants to prove that their reasonable expectation of privacy was violated by the government. Exceptions to the warrant requirement also exist, such as consent, lawful arrest, probable cause with exigent circumstances, and searches of abandoned property or open fields.
The Fourth Amendment continues to be a subject of debate, with ongoing discussions about its relevance and applicability in the modern world.
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Unreasonable searches and seizures
The Fourth Amendment to the United States Constitution, part of the Bill of Rights, was ratified on December 15, 1791. It protects the American people from "unreasonable searches and seizures". The official text is as follows:
> "The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized."
The Fourth Amendment was created in response to increasing infringements on privacy in the colonies and England. In England, "general warrants" were used to authorise the search of a person's belongings if they were suspected of being political enemies. In the colonies, "writs of assistance" were used to conduct warrantless searches for untaxed items. Both were challenged in court, but only ""general warrants" were considered a violation of the law.
The Fourth Amendment requires that every search or seizure of an individual's home and property be authorised by a judge beforehand, and that the operation is conducted on the grounds of "probable cause". This has been interpreted to mean that some seizures, even under warrants, could be deemed unreasonable.
The Fourth Amendment has been frequently debated in recent years, as police and intelligence agencies in the United States have engaged in controversial activities. The federal government has conducted bulk collections of Americans' telephone and internet data as part of the War on Terror. Critics argue that these programs are too widespread and invasive to be justified by the Fourth Amendment.
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Requirements for issuing warrants
The Fourth Amendment to the United States Constitution is part of the Bill of Rights. It prohibits unreasonable searches and seizures and sets requirements for issuing warrants.
The Fourth Amendment sets out several requirements that must be met for a warrant to be issued. These include:
- Warrants must be issued by a judge or magistrate: A warrant is a written court order signed by a judge or magistrate authorizing a police officer to conduct a search, seizure, or arrest. The courts deem searches, seizures, and arrests without a valid warrant presumptively invalid.
- Probable cause: Warrants must be justified by probable cause, which must be supported by an oath or affirmation from a law enforcement officer. The officer must confirm that they have not knowingly or intentionally made a false statement supporting the warrant and that they did not make any statements in reckless disregard of the truth.
- Particularity: The warrant must particularly describe the place to be searched and the persons or things to be seized. This requirement helps to limit the invasion of privacy by specifying the person to be seized, the place to be searched, and the evidence to be sought.
The Fourth Amendment also establishes that searches and seizures without a warrant are generally unreasonable and unconstitutional. However, there are some exceptions to this requirement, known as "specifically established and well-delineated exceptions," which apply in exceptional circumstances beyond the normal need for law enforcement.
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General warrants
The Fourth Amendment (Amendment IV) to the United States Constitution is part of the Bill of Rights. It was introduced as a response to the use of 'general warrants' during the colonial era, which allowed British officers to search homes without restraint for evidence of criminal activity.
> "...whereby any officer or messenger may be commanded to search suspected places without evidence of a fact committed, or to seize any person or persons not named, or whose offense is not particularly described and supported by evidence, are grievous and oppressive and ought not to be granted."
The Fourth Amendment sets out requirements for issuing warrants: warrants must be issued by a judge or magistrate, justified by probable cause, supported by oath or affirmation, and must particularly describe the place to be searched and the persons or things to be seized. The amendment's aim was to prevent the government's unrestrained power to search and seize, ensuring that searches and seizures were 'reasonable'.
The Fourth Amendment has been interpreted and applied in numerous court cases, with early decisions limiting its scope to physical intrusions of property or persons. However, in Katz v. United States (1967), the Supreme Court held that its protections extend beyond physical locations to include intrusions on the privacy of individuals. This has been further developed in cases such as Carpenter v. United States, which ruled that law enforcement must obtain a search warrant before accessing cell site location information (CSLI).
The Fourth Amendment continues to shape case law and influence court decisions, ensuring that searches and seizures are conducted within constitutional limits.
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Writs of assistance
The Fourth Amendment (Amendment IV) to the United States Constitution is part of the Bill of Rights, which was ratified in 1791. The amendment prohibits unreasonable searches and seizures and sets requirements for issuing warrants. This amendment was created in response to the increasing infringements on privacy in the colonies and in England.
In 1760, upon the death of King George II, the authorities were required to obtain new writs. James Otis challenged the writs in a Boston court in 1761, arguing that the authorizing statutes were invalid because they conflicted with England's constitution. Otis lost the case, but his arguments were widely cited in the colonies and attributed by some as a spark that led to the Revolution. John Adams, for example, included a requirement that all searches must be "reasonable" in Article XIV of the Massachusetts Declaration of Rights, enacted in 1780 as part of the Massachusetts Constitution. This, along with the Virginia Declaration of Rights (1776) prohibition of the use of general warrants, served as a basis for the language of the Fourth Amendment.
The Fourth Amendment thus protects against the government's use of writs of assistance and general warrants. It requires that warrants be issued by a judge or magistrate, justified by probable cause, supported by oath or affirmation, and must particularly describe the place to be searched and the persons or things to be seized.
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Frequently asked questions
The Fourth Amendment is part of the United States Constitution's Bill of Rights. It prohibits unreasonable searches and seizures and sets requirements for issuing warrants.
In the late 18th century, "general warrants" and "writs of assistance" were used in Britain and the colonies to pursue and search the belongings of individuals without any cause. This led to famous court cases such as Wilkes v. Wood (1763) and Entick v. Carrington (1765), where judges decided that such warrants violated English common law.
The Fourth Amendment added protections against unreasonable searches and seizures, requiring warrants to be issued by a judge or magistrate, justified by probable cause, supported by oath or affirmation, and describing the specific places to be searched and items to be seized.
The Fourth Amendment has been frequently debated in recent years, especially with the rise of new technologies and the War on Terror. Courts have had to balance individual privacy rights with the need for law enforcement to collect evidence and maintain national security. The amendment has been invoked in cases involving mass surveillance, bulk data collection, and aggressive police tactics.

























