“The House of Every One Is His Castle” A History of the Fourth Amendment
English foundations: from “castle” to constraints on general warrants
If you trace the Fourth Amendment to the United States Constitution back far enough, you end up at the London apartment front door of Richard Gresham in 1604. Berisford’s now deceased roommate, George Berisford, owed a debt to Peter Semayne. Semayne obtained a civil writ of attachment, but the Sheriff of London was denied entry into the apartment in spite of a threat by the Sheriff to break and enter into the home. The resulting civil suit laid the groundwork for the Fourth Amendment. In Semayne’s Case (1604), England’s Court of King’s Bench announced the now-famous maxim that “the house of every one is to him as his castle,” an early recognition that the home marks a legal threshold the state may cross only with lawful authority.[1] This “castle” principle seeded centuries of doctrine limiting how officials may enter and search private dwellings.
Seventeenth- and eighteenth-century English courts translated that principle into concrete constraints—most notably against general warrants. In Wilkes v. Wood (1763) and Huckle v. Money (1763), juries punished executive officers who ransacked homes under broad, nonspecific warrants, treating such raids as unlawful trespasses.[2] The capstone came in Entick v. Carrington (1765), where Lord Camden held that state messengers who broke into John Entick’s home and seized his papers acted without legal authority; government agents, no less than private citizens, must point to positive law for their actions.[3] Entick became the canonical statement against general warrants and a lodestar for the American founding generation.
Colonial America: writs of assistance and a political awakening
Across the Atlantic, British customs officials relied on writs of assistance—open-ended search powers to ferret out smuggled goods. Daniel Malcom, a wealth Boston merchant, learned this fact in September 1766. The customs inspectors who showed up that day did not need to specify the place the were searching or what they were looking for. An angry crowd, which included Paul Revere, gathered outside the home, effectively ending the search. In an earlier court case, James Otis Jr. delivered a blistering argument against these writs, calling them “the worst instrument of arbitrary power.” John Adams, who listened, later wrote that “then and there the child Independence was born.”
When the colonies became states, they enshired protections into their own charters. Virginia’s 1776 Declaration of Rights condemned general warrants as “grievous and oppressive,” and Massachusetts’s 1780 Constitution guaranteed security from unreasonable searches and seizures while demanding particularized warrants grounded in oath and probable cause.[5] These state texts supplied both principles and phrasing later used in the federal amendment.
Authorship of the Fourth Amendment belongs principally to James Madison. On June 8, 1789, responding to ratification-era promises and Anti-Federalist concerns, he introduced a slate of amendments in the House of Representatives that distilled state proposals into national guarantees. Congress refined his list and sent twelve proposals to the states; ten were ratified on December 15, 1791. Madison’s search-and-seizure clause—protecting “persons, houses, papers, and effects,” condemning “unreasonable searches and seizures,” and requiring warrants based on probable cause and particular description—remained recognizably his.[6]
From trespass to privacy
The principles of the Fourth Amendment were rarely challenged on a federal level through the 18th and 19th centuries. The bright line rule of no warrantless government entry into a one’s castle remained largely intact. Technology then forced doctrinal change.
Invented in 1886 and popularized in early 20th century by Henry Ford’s affordable Model T, the automobile was a revolution in its own right. Criminals took advantage of the easy method of transporting contraband and committing crimes, skyrocketing in popularity during Prohibition. At this stage of Constitutional law and search warrant requirements, police officers needed to stop a motor vehicle, develop probable cause, drive to a courthouse, obtain a warrant, and return to the motor vehicle, which undoubtably was miles away and occupants enjoying the illegal hooch. The automobile provided a massive advantage to the criminals: a method of committing crime virtually untouchable.
In 1925, federal law enforcement had probable cause to believe George Carroll and John Kiro were transporting alcohol in Michigan. Agents located the vehicle traveling on a Detroit street, stopped it, searched it, and found 68 quarts of whiskey and gin. The warrantless seizure issue was appealed to the US Supreme Court. In Carroll v US (1925), the court carved out an exception to Fourth Amendment. The change is what Stanford Law Professor Orin Kerr describes in his book The Digital Fourth Amendment as an “Equilibrium Adjustment”. The Fourth Amendment was giving criminals too much protection (i.e. warrant requirement extension to motor vehicles) and a shift in the rules was needed to balance the government’s interest and personal protections. Carroll gave birth to the “motor vehicle exception”: ability to conduct a warrantless search of a motor vehicle with probable cause.
In 1928, the US Supreme Court addressed another groundbreaking form of new technology, the telephone. In a narrow 5-4 decision, the Court gave a nod to the bright line rule of physical government intrusion into a protected location and held that warrantless wiretapping of telephone lines without physical trespass was not a search in Olmstead v US. But Justice Brandeis forecasted coming attractions when in his dissent he warned of “insidious encroachments” by new means. Four decades later, a listening device attached to a public telephone would be that encroachment to change the law.
George Katz used public telephones to run his illegal bookmaking business. FBI agents installed a listening device to the telephone booth Katz would use. In an appeal to the US Supreme Court, the bright line rule of physical trespass in Olmstead was overruled, declaring that “the Fourth Amendment protects people, not places,” and introducing the reasonable-expectation-of-privacy framework that could adapt to innovation.[9]
The modern turn: homes, bodies, and bytes
As surveillance tools proliferated, the Court looked through Katz’s privacy lens with renewed attention to property and home sanctity. Agents illegally used a thermal imager to observed excessive heat radiating from a suspected marijuana grow house in Kyllo v. United States (2001). Justices ruled a GPS tracker to a car as a “search”, triggering the warrant requirement of the Fourth Amendment, in Jones v US (2014). Florida v. Jardines (2013) ruled that bringing a drug-sniffing dog to a home’s front porch—its curtilage—is a search.
The Digital Age renewed Fourth Amendment analysis in a rapidly evolving society. All police officers know the principles of “search incident to arrest”, which grants permission to search the body and pockets of an arrested party for weapons and evidence of criminal activity. And early in Digital Age, the US Supreme Court extended this principle to a “pager” or “beeper”: a wireless telecommunications device that receives and displays alphanumeric or voice messages. Law enforcement was able to conduct a warrantless search of a pager for a few dozen phone numbers when obtained legally during an arrest. The Court decided to treat devices with massive storage differently.
In Riley v. California, 573 U.S. 373 (2014), the Court held that the search-incident-to-arrest exception does not let officers browse the digital contents of a cellphone without a warrant. The rationale was straightforward: a modern phone is a “minicomputer” holding years of emails, photos, app data, location history, and more—far beyond what offenders could carry on their person in a pre-digital era. As Chief Justice Roberts wrote in the 9-0 decision:
That is like saying ride on horseback is materially indistinguishable from a flight to the moon. Both are ways of getting from point A to point B, but little else justifies lumping them together. Modern cell phones, as a category, implicate privacy concerns far beyond those implicated by the search of a cigarette pack, a wallet, or a purse.
Next, Carpenter v. United States, 138 S. Ct. 2206 (2018), addressed historical cell-site location information (CSLI) obtained from a wireless carrier. The government had argued that, under the third-party doctrine, no warrant was needed because users “shared” their location data with a phone company.
The third-party doctrine originated in United States v. Miller, 425 U.S. 435 (1976) (bank records) and Smith v. Maryland, 442 U.S. 735 (1979) (dialed numbers via a pen register). The doctrine said people lack a reasonable expectation of privacy (standard for the warrant requirement set out in Katz) in information voluntarily conveyed to third parties. For decades, that meant subpoena- or court-order-level process (rather than a warrant) could often be used by law enforcement to obtain business records.
The Carpenter Court held since long-term CSLI is deeply revealing and retrospective, enabling “near perfect surveillance.” As a result, officers generally need a warrant supported by probable cause to obtain historical CSLI, again with room for exigent circumstances. Carpenter did not overrule Miller or Smith, but it carved out a significant limit: when third-party records are so comprehensive and revealing—like long-term CSLI—the Fourth Amendment may still require a warrant. In other words, the Court is recalibrating privacy expectations for the volume, sensitivity, and persistence of digital data. Expect that analysis to extend beyond CSLI to certain categories of cloud, app, or sensor data where scale and detail approximate continuous surveillance.
Enter the mosaic theory. First developed in cases like United States v. Maynard, 615 F.3d 544 (D.C. Cir. 2010) and influential in United States v. Jones, 565 U.S. 400 (2012) (through concurrences), the idea is that aggregated data points can create a “mosaic” more intrusive than any single snapshot. One license-plate scan or a single GPS ping may be modest, but weeks of pings or scans can reconstruct a person’s life—home, work, worship, medical visits—triggering Fourth Amendment protection even if each piece alone might not. Carpenter reflects this logic: duration and depth matter.
Digital evidence remains vital, but courts are demanding tighter alignment between investigative methods and the profound sensitivity of modern data. Adapting warrant practice and narrowing requests will protect prosecutions—and the Constitution—alike.
The core anxiety of unfettered government intrusion has not changed. From Semayne’s castle and Camden’s condemnation of general warrants to Madison’s phrasing and modern cases about GPS and smartphones, the constant is a demand for justification—probable cause, particularity, and, absent exigency, a warrant—before the state may rummage through a person’s life. That continuity lets the Fourth Amendment evolve without unmooring from its original purpose.
Front doors are no longer the only thresholds that matter. We carry our “papers and effects” in pockets and clouds, and our movements are logged by cell towers, license plate readers, and video camera. Courts today decide whether new techniques—thermal scans, GPS trackers, tower dumps, dog sniffs at porches—count as “searches,” and if so, what process is due. The through-line from Semayne to Carpenter is not a fixed rule but a balancing act. The goal posts are constantly moving as new technology is leveraged in criminal investigations which the courts are sometimes viewing through a 17th century lens.
Law enforcement is committed to upholding the Constitution while trying to make the world a better place through comprehensive investigations
That commitment animates this project
