From Writs of Assistance to Your Cell Phone, the Fourth Amendment's Long Fight

Pick up your phone. Go ahead, I'll wait. Think about what is in it. Your messages to your wife. Your bank. Your doctor's portal. Every photo of every kid at every birthday. A map of everywhere you went last Tuesday and where you slept last night. The searches you would be embarrassed to read aloud. The Founders, who kept their private papers in a desk drawer and their secrets in their heads, could not have imagined it. And yet if you want to know whether a police officer can look through that phone, you will find your answer in a sentence written in 1789 by men who had just finished a fight over smuggled goods in Boston.

That is what I love about this story. A principle that began as a dispute between merchants and customs agents in Boston ended up deciding whether the government can read your texts. The words did not change. The world did, and the courts had to decide whether the words still meant what they said. Let me take you through it, from the beginning.

The writs, and a lawyer who quit his job

In the 1750s and 1760s, Britain tried to enforce its trade laws in the American colonies, and smuggling was common. To catch smugglers, customs officers used a document called a writ of assistance. It was a general warrant. It did not name a person or a house. It did not require the officer to swear that he had evidence. It let the holder go into any home, warehouse or ship, anywhere, at any time, and search for goods on which the duty had not been paid. The writ lasted for the life of the king, and officers could, and did, make use of the power for their own purposes.

When King George II died in 1760, the writs were due to expire, and the customs officers asked the Massachusetts courts to renew them. In February 1761, in a Boston courtroom, a lawyer named James Otis Jr. argued against them. Otis held a post as a crown law officer in the colony, and he resigned it rather than argue for the writs. He took the other side, and a young lawyer in the audience named John Adams took notes. Years later Adams looked back on that day and said it was the moment American independence was born. The phrase is famous, and the full text of Adams's recollection is easy to look up. Otis lost the case. The writs were upheld. But the argument was the seed.

Entick, Wilkes, and the Englishman's castle

Across the Atlantic, English courts were arriving at the same principle. In the 1760s, the government issued general warrants to hunt for authors of critical pamphlets. In Wilkes v. Wood (1763), a court held that a general warrant to search for the author of a pamphlet attacking the king's speech was unlawful. And in Entick v. Carrington (1765), Lord Camden, the Chief Justice of the Court of Common Pleas, held that the king's messengers had no right to break into the home of John Entick, rummage through his papers and seize them, under a warrant signed by a Secretary of State. The government argued that state necessity justified the practice. The court answered that if the government claims a power, it must point to a law that grants it.

Think about the strength of that idea. The government does not get to search because it says it has good reasons. It has to show where the law allows it. That principle, brought across the ocean, shaped how Americans thought about their own rights. A man's house, the old saying went, is his castle. It was never a legal absolute, but it was a good rule of thumb: the king can come in only by the front door, with the law in his hand.

The text

After independence, the new states wrote their own declarations of rights, and several included protections against general warrants. When the Constitution was proposed in 1787, it lacked a bill of rights, and many people refused to ratify without one. James Madison drafted amendments, and Congress sent them to the states in 1789. They were ratified in 1791. The Fourth Amendment reads, in full:

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.

Read it slowly and you can hear the writs of assistance in every clause. "Persons, houses, papers, and effects": the things the customs officers rifled through. "Unreasonable": the standard. "Probable cause, supported by Oath or affirmation": the opposite of a general warrant that required no evidence. "Particularly describing the place to be searched, and the persons or things to be seized": the opposite of a writ that named nothing. This is a text written by people who had been on the wrong end of the thing it forbids. We take the same approach to reading texts in Originalism Explained for People Who Skipped Law School.

The exclusionary rule: Weeks to Mapp

For more than a century, the amendment was mostly a restraint on federal officers, and the question of what happened when they broke the rule was unsettled. In Weeks v. United States (1914), the Court held that evidence seized in violation of the amendment could not be used in a federal trial. That is the exclusionary rule. For decades, though, it did not bind the states.

The big change came in Mapp v. Ohio (1961). Cleveland police, looking for a suspect in a bombing, forced their way into the home of Dollree Mapp, waved a piece of paper they said was a warrant, and searched her house. They did not find the suspect. They found some materials they said were obscene, and she was convicted for possessing them. The Supreme Court held, six to three, that evidence obtained in an unconstitutional search must be excluded from state courts as well.

Conservatives have long argued about this rule. The objection is that a guilty person may go free because an officer made a mistake. The rule's defenders say there is no other way to make the right mean anything. The Court has narrowed the rule over time. In United States v. Leon (1984), it created a good-faith exception for officers who reasonably rely on a warrant that later proves defective. The argument over the rule is a good argument, and it shows that you can believe in the Fourth Amendment and still disagree about how to enforce it.

Katz: the phone booth

For the first half of the twentieth century, the Court read the amendment in a literal way. In Olmstead v. United States (1928), federal agents tapped telephone lines outside a bootlegger's home. The Court held, five to four, that this was not a search because the agents had not entered his property. Justice Brandeis dissented, writing that the Framers had conferred "the right to be let alone." It was a minority view for nearly forty years.

Then came Katz v. United States (1967). Federal agents attached a listening device to the outside of a public phone booth to record Charles Katz placing bets. They did not enter the booth. Under Olmstead that would have been fine. The Court held that it was a search. Justice Stewart wrote that the Fourth Amendment "protects people, not places." Justice Harlan's concurrence set out a two-part test that the Court later adopted: did the person have an actual expectation of privacy, and is that expectation one society is prepared to recognize as reasonable? Only Justice Black dissented.

The "reasonable expectation of privacy" test has its critics, including conservatives. Justice Scalia thought it was circular: the Court says you have a reasonable expectation if the Court says it is reasonable. So he and others looked back toward the text and the idea of property.

The third-party doctrine

A few years after Katz, the Court drew a limit. In United States v. Miller (1976), the Court held that bank records are not protected because the customer has given them to the bank. In Smith v. Maryland (1979), it held that the numbers you dial on a phone are not protected because you've shared them with the phone company. This is called the third-party doctrine: what you voluntarily give to someone else, you cannot expect to stay private.

In 1979, that sounded sensible. Dialed numbers were a small amount of information. Then came the digital age, when nearly everything about your life is held by a third party. A rule built for a ledger of dialed numbers meets a world in which a company holds your location, your searches and your communications. This is where the old text has to meet the new technology.

Kyllo and Jones: technology tests the line

In Kyllo v. United States (2001), federal agents pointed a thermal imager at a home to detect heat from grow lamps. Justice Scalia, writing for a five-to-four Court, held that using technology not in general public use to learn about the inside of a home is a search. We discuss that case and its author in Antonin Scalia Sided With Flag Burners and Defendants, and That Is the Point.

In United States v. Jones (2012), police attached a GPS tracking device to a Jeep registered to the wife of a nightclub owner named Antoine Jones, and followed the car's movements for four weeks. The Court was unanimous that this was a search. Justice Scalia wrote for five justices that physically attaching a device to someone's property to gain information is a trespass of the kind the Framers had in mind. Justice Alito, joined by three others, agreed with the result on different grounds: long-term monitoring of a person's movements can violate expectations of privacy even if no property is touched. Justice Sotomayor wrote separately to say that the third-party doctrine deserved a fresh look.

Riley and Carpenter: the cell phone cases

Now we reach your phone.

In Riley v. California (2014), police arrested David Riley and looked through his smartphone without a warrant. Under a long-standing rule, officers can search a person they arrest and the items on him, to protect themselves and prevent the destruction of evidence. The government said that rule covered a phone. Chief Justice Roberts, writing for a unanimous Court, said no. A phone, he wrote, is nothing like a wallet or a cigarette pack; it holds the privacies of life. The answer to what police must do before searching a phone, in his words, was simple: get a warrant. Nine justices, from every wing of the Court, agreed.

In Carpenter v. United States (2018), the question was location records. The FBI was investigating a series of robberies, and it obtained from Timothy Carpenter's wireless carriers about 127 days of cell-site location records, roughly 12,900 location points, which works out to about 100 data points a day (12,900 divided by 127 is about 101.6). The government got them with a court order under a federal statute that required less than probable cause. The Court held, five to four, that obtaining that history is a search that generally requires a warrant. Chief Justice Roberts wrote the opinion, joined by Justices Ginsburg, Breyer, Sotomayor and Kagan.

Here is the part conservatives should find interesting. The four dissenters were Justices Kennedy, Thomas, Alito and Gorsuch. Each of them wrote separately. Kennedy, Thomas and Alito argued that the records belonged to the phone company and fell under the third-party doctrine, and that the Court was departing from precedent. Justice Gorsuch argued from a different angle: that the real question was whether the records were your property, and he suggested that the law of bailment, the way the law treats things entrusted to others, might give you a property interest in your data. This was no neat partisan split. It was a fight among conservatives about how to apply the Fourth Amendment to the digital age, and the Chief Justice, a conservative, wrote the opinion protecting the phone.

The decision was explicitly narrow. It did not overturn Miller or Smith, and it did not address real-time tracking or other kinds of data. What is a search under the Fourth Amendment will keep being litigated, and Congress can act too. The federal law on stored communications dates from 1986, and the world has changed a great deal. For the debate over surveillance by national security agencies, see FISA, Section 702 and the Fourth Amendment, What the Law Allows.

What it means for your family

The principle is the same one Otis argued in Boston. The government may not rummage. It has to show a reason, to a neutral person, before it searches what is yours. Courts have applied that to houses, to papers, to cars and now to the glowing rectangle in your pocket. When a conservative says he believes in limited government, this is what it looks like in practice: the government must ask permission, with evidence, before it looks through your life.

A few sensible habits follow. If an officer asks to search you, your car or your phone, you may say clearly that you do not consent, and then do not physically resist. Ask whether you are free to go. If you are arrested, call a lawyer. These aren't tricks. They are the rights that the writs of assistance denied to the colonists.

The bottom line

• The Fourth Amendment was written against general warrants. Every clause answers a specific abuse, and every modern case asks whether a new technology reopens the old abuse.
• The Supreme Court held unanimously in Riley that police need a warrant to search your phone after an arrest, and held in Carpenter, five to four, that they generally need one for long-term location records.
• The justices who split in Carpenter were mostly conservatives arguing about method. You can defend the text and disagree about the application.
• Say plainly that you do not consent to a search, do not resist, and call a lawyer. Know your rights before you need them.
• Ask your representatives whether the federal laws on electronic records are up to date. Congress can protect your privacy without waiting for a court.