The Fourth Amendment
Ratified in 1791, the Fourth Amendment protects Americans from unreasonable searches and seizures by the government. It requires warrants to be based on probable cause and to specifically describe what may be searched or seized. Today it is the amendment most tested by digital technology, surveillance, and new law enforcement tools.
The Text of the Fourth Amendment
"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."
Two Clauses, One Protection
The Fourth Amendment contains two distinct clauses. The Committee of Eleven separated them during the drafting process in 1789, though no records survive explaining why. Together they create a system for protecting privacy from government intrusion.
The Reasonableness Clause
"The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated..."
This clause is the broad prohibition. It bars all unreasonable searches and seizures. What counts as unreasonable has been interpreted, debated, and refined by courts for over two centuries.
The Warrant Clause
"...and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized."
This clause sets the conditions for valid warrants. A warrant must be based on probable cause, sworn by oath, and specifically identify what is being searched and what is being sought.
Why Was It Written?
The Fourth Amendment was a direct response to colonial-era abuses by the British Crown. Two specific legal instruments had enraged the colonists in the decades before the Revolution.
The first was the general warrant, a broad court order authorizing government agents to search any person or place they chose, without specifics, in pursuit of evidence. The second was the writ of assistance, a standing general warrant used by British customs officials in the American colonies to search homes and warehouses for smuggled goods without restriction, without time limits, and without any particular suspicion.
Colonial lawyer James Otis Jr. delivered a famous 1761 argument in a Boston courtroom against writs of assistance. John Adams later called Otis's speech the spark of the Revolution, writing that the child independence was born in that moment. The Fourth Amendment was written to ensure that no American government could ever wield that kind of unlimited search power again.
James Madison drafted the Fourth Amendment as part of the Bill of Rights, drawing heavily on declarations of rights from Virginia and other states. It was ratified on December 15, 1791.
Historical Roots
1215
Magna Carta
Chapter 39 established that no free man shall be seized or imprisoned except by lawful judgment of his peers. This foundational document seeded the concept that government power over persons and property must be constrained by law.
1760s
Writs of Assistance in the Colonies
British customs officials used general search warrants with no expiration and no specificity to search colonial homes and businesses for smuggled goods. James Otis Jr.'s 1761 legal challenge to writs of assistance in Boston became a rallying point for colonial resistance.
1765
Entick v. Carrington (England)
An English court ruled that the King's messengers had no authority to search a journalist's home without specific legal justification. The case established that general warrants were illegal under English common law and was cited directly by American courts in the founding era.
1789
Madison drafts the Fourth Amendment
James Madison introduced the Fourth Amendment to the House of Representatives on June 8, 1789. His draft focused on general warrants. The Committee of Eleven divided the text into the two-clause structure that exists today.
1791
Ratification
The Fourth Amendment was ratified as part of the Bill of Rights on December 15, 1791. It applied only to the federal government until the Supreme Court incorporated it against the states through the 14th Amendment in Mapp v. Ohio (1961).
Did You Know?
The Fourth Amendment protects people, not places. That means if you have a reasonable expectation of privacy somewhere, the Fourth Amendment protects you there, regardless of whether the place itself is private.
In Riley v. California (2014), the Supreme Court unanimously ruled that police must get a warrant before searching a cell phone, even after a lawful arrest. Chief Justice Roberts wrote that a phone can hold more personal information than an entire home.
Cars receive significantly less Fourth Amendment protection than homes. Police can search your vehicle without a warrant if they have probable cause to believe it contains contraband or evidence of a crime.
In 2026, the Supreme Court is considering United States v. Chatrie, a case about whether geofence warrants, which demand location data from every phone in a geographic area, violate the Fourth Amendment.