Minnesota v. Olson (1990)

495 U.S. 91 (1990)

Vote: 7-2
Decision: Affirmed
Majority: White, joined by Brennan, Marshall, Stevens, O’Connor, Scalia, and Kennedy
Concurrence: Stevens
Concurrence: Kennedy
Dissent: Rehnquist
Dissent: Blackmun

Justice WHITE delivered the opinion of the Court.

The police in this case made a warrantless, nonconsensual entry into a house where Olson was an overnight guest and arrested him. The issue is whether the arrest violated Olson’s Fourth Amendment rights. We hold that it did.

Shortly before 6 a.m. on Saturday, July 18, 1987, a lone gunman robbed an Amoco gasoline station in Minneapolis, Minnesota, and fatally shot the station manager. A police officer heard the police dispatcher report and suspected Joseph Ecker. The officer and his partner drove immediately to Ecker’s home, arriving at about the same time that an Oldsmobile arrived. The Oldsmobile took evasive action, spun out of control, and came to a stop. Two men fled the car on foot. Ecker, who was later identified as the gunman, was captured shortly thereafter inside his home. The second man escaped.

Inside the abandoned Oldsmobile, police found a sack of money and the murder weapon. They also found a title certificate with the name Rob Olson crossed out as a secured party, a letter addressed to a Roger R. Olson of 3151 Johnson Street, and a videotape rental receipt made out to Rob Olson and dated two days earlier. The police verified that a Robert Olson lived at 3151 Johnson Street.

The next morning, Sunday, July 19, a woman identifying herself as Dianna Murphy called the police and said that a man by the name of Rob drove the car in which the gas station killer left the scene, and that Rob was planning to leave town by bus. About noon, the same woman called again, gave her address and phone number, and said that a man named Rob had told a Maria and two other women, Louanne and Julie, that he was the driver in the Amoco robbery. The caller stated that Louanne was Julie’s mother, and that the two women lived at 2406 Fillmore Northeast. The detective-in-charge who took the second phone call sent police officers to 2406 Fillmore to check out Louanne and Julie. When police arrived, they determined that the dwelling was a duplex and that Louanne Bergstrom and her daughter Julie lived in the upper unit, but were not home. Police spoke to Louanne’s mother, Helen Niederhoffer, who lived in the lower unit. She confirmed that a Rob Olson had been staying upstairs, but was not then in the unit. She promised to call the police when Olson returned. At 2 p.m., a pickup order, or “probable cause arrest bulletin,” was issued for Olson’s arrest. The police were instructed to stay away from the duplex.

At approximately 2:45 p.m., Niederhoffer called police and said Olson had returned. The detective-in-charge instructed police officers to go to the house and surround it. He then telephoned Julie from headquarters and told her Rob should come out of the house. The detective heard a male voice say “tell them I left.” Julie stated that Rob had left, whereupon, at 3 p.m., the detective ordered the police to enter the house. Without seeking permission and with weapons drawn, the police entered the upper unit and found respondent hiding in a closet. Less than an hour after his arrest, respondent made an inculpatory statement at police headquarters.

The Hennepin County trial court held a hearing and denied respondent’s motion to suppress his statement. The statement was admitted into evidence at Olson’s trial, and he was convicted on one count of first degree murder, three counts of armed robbery, and three counts of second degree assault. On appeal, the Minnesota Supreme Court reversed. The court ruled that respondent had a sufficient interest in the Bergstrom home to challenge the legality of his warrantless arrest there, that the arrest was illegal because there were no exigent circumstances to justify a warrantless entry, and that respondent’s statement was tainted by that illegality and should have been suppressed.

Because the admission of the statement was not harmless beyond reasonable doubt, the court reversed Olson’s conviction and remanded for a new trial.

We granted the State’s petition for certiorari, and now affirm.

It was held in Payton v. New York (1980), that a suspect should not be arrested in his house without an arrest warrant, even though there is probable cause to arrest him. The purpose of the decision was not to protect the person of the suspect but to protect his home from entry in the absence of a magistrate’s finding of probable cause. In this case, the court below held that Olson’s warrantless arrest was illegal because he had a sufficient connection with the premises to be treated like a householder. The State challenges that conclusion.
. …

The State argues that Olson’s relationship to the premises does not satisfy the 12 factors which in its view determine whether a dwelling is a “home.” Aside from the fact that it is based on the mistaken premise that a place must be one’s “home” in order for one to have a legitimate expectation of privacy there, the State’s proposed test is needlessly complex. We need go no further than to conclude, as we do, that Olson’s status as an overnight guest is alone enough to show that he had an expectation of privacy in the home that society is prepared to recognize as reasonable.

As recognized by the Minnesota Supreme Court, the facts of this case are similar to those in Jones v. United States (1960). In Jones, the defendant was arrested in a friend’s apartment during the execution of a search warrant and sought to challenge the warrant as not supported by probable cause.

. …

The Court ruled that Jones could challenge the search of the apartment because he was “legitimately on [the] premises,”.  Although the “legitimately on [the] premises” standard was rejected in Rakas as too broad, the Rakas Court explicitly reaffirmed the factual holding in Jones:

“We do not question the conclusion in Jones that the defendant in that case suffered a violation of his personal Fourth Amendment rights if the search in question was unlawful. … ”

“We think that Jones, on its facts, merely stands for the unremarkable proposition that a person can have a legally sufficient interest in a place other than his own home so that the Fourth Amendment protects him from unreasonable governmental intrusion into that place.”

. … The State emphasizes that, in this case, Olson was never left alone in the duplex or given a key, whereas, in Jones, the owner of the apartment was away and Jones had a key with which he could come and go and admit and exclude others. These differences are crucial, it is argued, because, in not disturbing the holding in Jones, the Court pointed out that, while his host was away, Jones had complete dominion and control over the apartment and could exclude others from it. We do not understand Rakas, however, to hold that an overnight guest can never have a legitimate expectation of privacy except when his host is away and he has a key, or that only when those facts are present may an overnight guest assert the “unremarkable proposition,” that a person may have a sufficient interest in a place other than his home to enable him to be free in that place from unreasonable searches and seizures.

To hold that an overnight guest has a legitimate expectation of privacy in his host’s home merely recognizes the everyday expectations of privacy that we all share. Staying overnight in another’s home is a longstanding social custom that serves functions recognized as valuable by society. We stay in others’ homes when we travel to a strange city for business or pleasure, when we visit our parents, children, or more distant relatives out of town, when we are in between jobs or homes, or when we house-sit for a friend. We will all be hosts and we will all be guests many times in our lives. From either perspective, we think that society recognizes that a houseguest has a legitimate expectation of privacy in his host’s home.

From the overnight guest’s perspective, he seeks shelter in another’s home precisely because it provides him with privacy, a place where he and his possessions will not be disturbed by anyone but his host and those his host allows inside. … Society expects at least as much privacy in these places as in a telephone booth — “a temporarily private place whose momentary occupants’ expectations of freedom from intrusion are recognized as reasonable,” Katz (Harlan, J., concurring).

. …

Because respondent’s expectation of privacy in the Bergstrom home was rooted in “understandings that are recognized and permitted by society,” it was legitimate, and respondent can claim the protection of the Fourth Amendment.

. …

This case requires us to determine whether the Minnesota Supreme Court was correct in holding that there were no exigent circumstances that justified the warrantless entry into the house to make the arrest.

The Minnesota Supreme Court applied essentially the correct standard in determining whether exigent circumstances existed. The court observed that

“a warrantless intrusion may be justified by hot pursuit of a fleeing felon, or imminent destruction of evidence, Welsh v. Wisconsin (1984), or the need to prevent a suspect’s escape, or the risk of danger to the police or to other persons inside or outside the dwelling.”

The court also apparently thought that, in the absence of hot pursuit, there must be at least probable cause to believe that one or more of the other factors justifying the entry were present and that in assessing the risk of danger, the gravity of the crime, and likelihood that the suspect is armed should be considered. Applying this standard, the state court determined that exigent circumstances did not exist.

We are not inclined to disagree with this fact-specific application of the proper legal standard. The court pointed out that, although a grave crime was involved, respondent “was known not to be the murderer, but thought to be the driver of the getaway car,” and that the police had already recovered the murder weapon.

“The police knew that Louanne and Julie were with the suspect in the upstairs duplex, with no suggestion of danger to them. Three or four Minneapolis police squads surrounded the house. The time was 3 p.m., Sunday. … It was evident the suspect was going nowhere. If he came out of the house, he would have been promptly apprehended.”

We do not disturb the state court’s judgment that these facts do not add up to exigent circumstances.

We therefore affirm the judgment of the Minnesota Supreme Court.

It is so ordered.

Excerpted by Makenna Perry

Minnesota v. Carter (1998)

525 U.S. 83 (1998)

Vote: 6-3
Decision: Reversed
Majority: Rehnquist joined by, O’Connor, Scalia, Kennady, Thomas, and Breyer
Concurrence: Scalia joined by Thomas
Concurrence: Kennedy
Concurrence: Breyer
Dissent: Ginsburg joined by Stevens and Souter

CHIEF JUSTICE REHNQUIST delivered the opinion of the Court.

Respondents and the lessee of an apartment were sitting in one of its rooms, bagging cocaine. While so engaged they were observed by a police officer, who looked through a drawn window blind. The Supreme Court of Minnesota held that the officer’s viewing was a search that violated respondents’ Fourth Amendment rights. We hold that no such violation occurred.

James Thielen, a police officer in the Twin Cities’ suburb … went to an apartment building to investigate a tip from a confidential informant. The informant said that he had walked by the window of a ground-floor apartment and had seen people putting a white powder into bags. The officer looked in the same window through a gap in the closed blind and observed the bagging operation for several minutes. He then notified headquarters, which began preparing affidavits for a search warrant while he returned to the apartment building. When two men left the building in a previously identified Cadillac, the police stopped the car. Inside were respondents Carter and Johns. As the police opened the door of the car to let Johns out, they observed a black, zippered pouch and a handgun, later determined to be loaded, on the vehicle’s floor. Carter and Johns were arrested, and a later police search of the vehicle the next day discovered pagers, a scale, and 47 grams of cocaine in plastic sandwich bags.

After seizing the car, the police returned to apartment 103 and arrested the occupant, Kimberly Thompson, who is not a party to this appeal. A search of the apartment pursuant to a warrant revealed cocaine residue on the kitchen table and plastic baggies similar to those found in the Cadillac. Thielen identified Carter, Johns, and Thompson as the three people he had observed placing the powder into baggies. The police later learned that while Thompson was the lessee of the apartment, Carter and Johns lived in Chicago and had come to the apartment for the sole purpose of packaging the cocaine. Carter and Johns had never been to the apartment before and were only in the apartment for approximately 2 1/2 hours. In return for the use of the apartment, Carter and Johns had given Thompson one-eighth of an ounce of the cocaine.

Carter and Johns were charged with conspiracy to commit a controlled substance crime in the first degree and aiding and abetting in a controlled substance crime in the first degree. … They moved to suppress all evidence obtained from the apartment and the Cadillac, as well as to suppress several post-arrest incriminating statements they had made. They argued that Thielen’s initial observation of their drug packaging activities was an unreasonable search in violation of the Fourth Amendment and that all evidence obtained as a result of this unreasonable search was inadmissible as fruit of the poisonous tree. The Minnesota trial court held that since, unlike the defendant in Minnesota v. Olson (1990), Carter and Johns were not overnight social guests but temporary out-of-state visitors, they were not entitled to claim the protection of the Fourth Amendment against the government intrusion into the apartment. The trial court also concluded that Thielen’s observation was not a search within the meaning of the Fourth Amendment. After a trial, Carter and Johns were each convicted of both offenses. The Minnesota Court of Appeals held that respondent Carter did not have “standing” to object to Thielen’s actions because his claim that he was predominantly a social guest was “inconsistent with the only evidence concerning his stay in the apartment, which indicates that he used it for a business purpose-to package drugs. … ”

A divided Minnesota Supreme Court reversed, holding that respondents had “standing” to claim the protection of the Fourth Amendment because they had” ‘a legitimate expectation of privacy in the invaded place.'”  (quoting Rakas v. Illinois (1978)). The court noted that even though “society does not recognize as valuable the task of bagging cocaine, we conclude that society does recognize as valuable the right of property owners or leaseholders to invite persons into the privacy of their homes to conduct a common task, be it legal or illegal activity. We, therefore, hold that [respondents] had standing to bring [their] motion to suppress the evidence gathered as a result of Thielen’s observations.” Based upon its conclusion that respondents had “standing” to raise their Fourth Amendment claims, the court went on to hold that Thielen’s observation constituted a search of the apartment under the Fourth Amendment, and that the search was unreasonable. We granted certiorari, 523 U. S. 1003 (1998), and now reverse.

The Minnesota courts analyzed whether respondents had a legitimate expectation of privacy under the rubric of “standing” doctrine, an analysis that this Court expressly rejected 20 years ago in Rakas. In that case, we held that automobile passengers could not assert the protection of the Fourth Amendment against the seizure of incriminating evidence from a vehicle where they owned neither the vehicle nor the evidence. Central to our analysis was the idea that in determining whether a defendant is able to show the violation of his (and not someone else’s) Fourth Amendment rights, the “definition of those rights is more properly placed within the purview of substantive Fourth Amendment law than within that of standing.” Thus, we held that in order to claim the protection of the Fourth Amendment, a defendant must demonstrate that he personally has an expectation of privacy in the place searched, and that his expectation is reasonable. …

… [T]he extent to which the Fourth Amendment protects people may depend upon where those people are. We have held that “capacity to claim the protection of the Fourth Amendment depends … upon whether the person who claims the protection of the Amendment has a legitimate expectation of privacy in the invaded place.” Rakas, supra.

The text of the Amendment suggests that its protections extend only to people in “their” houses. But we have held that in some circumstances a person may have a legitimate expectation of privacy in the house of someone else. In Minnesota v. Olson (1990), for example, we decided that an overnight guest in a house had the sort of expectation of privacy that the Fourth Amendment protects. We said:

“To hold that an overnight guest has a legitimate expectation of privacy in his host’s home merely recognizes the every day expectations of privacy that we all share. Staying overnight in another’s home is a longstanding social custom that serves functions recognized as valuable by society. We stay in others’ homes when we travel to a strange city for business or pleasure, when we visit our parents, children, or more distant relatives out of town, when we are in between jobs or homes, or when we house-sit for a friend. …

“From the overnight guest’s perspective, he seeks shelter in another’s home precisely because it provides him with privacy, a place where he and his possessions will not be disturbed by anyone but his host and those his host allows inside. We are at our most vulnerable when we are asleep because we cannot monitor our own safety or the security of our belongings. It is for this reason that, although we may spend all day in public places, when we cannot sleep in our own home we seek out another private place to sleep, whether it be a hotel room, or the home of a friend.”

. …

Respondents here were obviously not overnight guests, but were essentially present for a business transaction and were only in the home a matter of hours. There is no suggestion that they had a previous relationship with Thompson, or that there was any other purpose to their visit. Nor was there anything similar to the overnight guest relationship in Olson to suggest a degree of acceptance into the household. While the apartment was a dwelling place for Thompson, it was for these respondents simply a place to do business.

Property used for commercial purposes is treated differently for Fourth Amendment purposes from residential property. “An expectation of privacy in commercial premises, however, is different from, and indeed less than, a similar expectation in an individual’s home.” New York v. Burger (1987). And while it was a “home” in which respondents were present, it was not their home. …

If we regard the overnight guest in Minnesota v. Olson as typifying those who may claim the protection of the Fourth Amendment in the home of another, and one merely “legitimately on the premises” as typifying those who may not do so, the present case is obviously somewhere in between. But the purely commercial nature of the transaction engaged in here, the relatively short period of time on the premises, and the lack of any previous connection between respondents and the householder, all lead us to conclude that respondents’ situation is closer to that of one simply permitted on the premises. We therefore hold that any search which may have occurred did not violate their Fourth Amendment rights.

Because we conclude that respondents had no legitimate expectation of privacy in the apartment, we need not decide whether the police officer’s observation constituted a “search.” The judgments of the Supreme Court of Minnesota are accordingly reversed, and the cause is remanded for proceedings not inconsistent with this opinion.

It is so ordered.

Excerpted By Makenna Perry

Chatrie v. United States (2026)

609 U.S. ___ (2026)
No. 25-112

Vote: 6-3
Opinion: Justice Kagan
Decision: Vacated & Remanded
Majority: Justice Kagan, joined by Roberts, Sotomayor, Kavanaugh, and Jackson
Concurrence: Justice Jackson, joined by Sotomayor
Concurrence: Justice Gorsuch
Dissent: Justice Alito, joined by Thomas (Part I), Barret (Parts II-B, II-C-1 and II-C-2)
Dissent: Justice Barrett

JUSTICE KAGAN delivered the opinion of the Court.

In recent years, law enforcement officers have employed so-called geofence warrants to obtain information that technology companies collect about their users’ cell-phone locations. Suppose that investigators know a crime was committed at a particular place and time, but do not have a suspect. They may draw a “geofence”—a virtual perimeter—around the crime scene and get a warrant compelling a company to hand over data about the cell phones located in that area near the time of the crime. Following a process specified in the warrant, the company will turn over the cell-phone data and eventually identify by name one or more of the users thus disclosed.

The geofence warrant at issue here was directed to Google, and used to solve a bank robbery. Hundreds of millions of Google users have activated a service called Location History, which records the location of a user’s cell phone every two minutes or so. Through a geofence warrant, police officers required Google to turn over Location History data revealing cell phones within the vicinity of a bank at around the time it was robbed. At the end of the multi-step process described in the warrant, Google gave the police three names. The Federal Government soon charged one of the individuals thus identified, petitioner Okello Chatrie, with committing the crime.

….

…Today, more than nine in ten Americans own a smartphone. That means they are likely addicted to apps and other services, many of which collect and store “detailed information about all aspects of a person’s life.” Riley v California 573 U.S. 373 (2014).

….

This case concerns a form of cell-phone location data called “Location History,” which Google apps collect and store. Location History is what it sounds like—a time-stamped record of every place a cell phone has been. Every two minutes or so, Location History draws from an array of sources to log a cell phone’s location. Those sources include nearby Wi-Fi networks, Bluetooth beacons, and cell sites, as well as GPS and IP address information. When combined, the signals tracked can determine a cell phone’s location within 20 meters….

….

Google repeatedly prompts users to enable Location History, and over 500 million users worldwide have done so…. Google stores all Location History data in the cloud….

In the last decade, Google’s Location History data has also served another function, though this one unknown to most users: That data, as obtained through a geofence warrant, can enable law enforcement officers to solve hard-to solve crimes…. The goal, put simply, is to find out who was there and so who might have done it. (There are usually better ways to investigate an already-known suspect—like seeking only his location data.) And the mechanism is to use the offender’s cell phone as an identifying device. The warrant specifies a timeframe and maps an area (with the geofence as its perimeter), and demands information about the cell phones—and their users—present within it…. There is some uncertainty about how often the technique in fact works. But its use among law enforcement officers has flourished….

As those demands began to proliferate, Google worked with law enforcement officials to develop a three-step protocol to govern geofence warrants. At the first step, Google produces anonymized (i.e., no names attached) location data for all cell phones (or other devices) within the geofence—typically, a circle with a designated radius surrounding a latitude/longitude coordinate—during a specified timeframe. That data generally includes each phone’s latitude/longitude coordinate and corresponding timestamp; an estimate of that information’s accuracy; and a description of the information’s source (e.g., a Wi-Fi network, a cell site, or some other). The data at this stage shows each user’s location, every two minutes or so, within the geofence. At the second step of the process, officials review the data produced and typically ask Google to provide additional information for a subset of still-anonymized users. That new data is usually for a longer timeframe than first specified; it also shows the user’s location outside, as well as inside, the geofence. Finally, at the third step, officials demand the identities of a further subset of users—their names, email addresses, and phone numbers. Thus, the geofence warrant is designed to eventually produce a select number of identified users suspected of committing the crime under investigation.

On May 20, 2019, at about 4:50 p.m., a man robbed a credit union in Midlothian, Virginia. The robber presented a teller with a handwritten note demanding $100,000, threatening to hurt her and her family if she did not comply, and warning her that he had “boys on the lookout outside.” When the teller replied that she did not have access to that amount of money, the robber brandished a firearm. He ordered everyone in the bank to the ground, and forced the bank’s manager to open a safe and put $195,000 into a bag. The robber then left on foot with the money.

….

On June 14, the police officers thus applied to a Virginia magistrate for a geofence warrant directed to Google….

The warrant application went on to describe the three step process that the police would follow to obtain the location information sought. At step one, Google would produce anonymized location data for all cell phones within the geofence… (30 minutes before to 30 minutes after the robbery). At step two, police officers would “attempt to narrow down the list [of devices] by reviewing the time stamped location coordinates for each [device]…. Finally, at step three, police would again “attempt to narrow down the list by comparing this additional information regarding travel and time against the known time and location information that is specific to this crime.”….

…At the third and last step, the police again narrowed the list, this time to three users. Google responded with their identifying information. One of the three was Chatrie. The location data showed that he entered the geofenced area about ten minutes before the robbery, and headed toward a residential area of town immediately after leaving the bank.

Following further police work, a federal grand jury charged Chatrie with robbery and related firearms offenses. He moved to suppress the information that the police had obtained from Google. According to Chatrie, the officers had acquired that data through a Fourth Amendment search, and the warrant ostensibly authorizing that search was invalid.

….

We granted certiorari solely on the question whether the police violated the Fourth Amendment in obtaining Chatrie’s location data… The disputed Fourth Amendment question divides into two parts. First, did law enforcement officials conduct a search under the Fourth Amendment when they acquired Chatrie’s location data from Google? We hold that they did because an individual has a legitimate expectation of privacy in his cell-phone location data….

The Fourth Amendment protects “[t]he right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures.” The “basic purpose” of that Amendment, our precedents say, is “to safeguard the privacy and security of individuals against arbitrary invasions by governmental officials.” Carpenter v. United States, (2018) (quoting Camara v. Municipal Court of City and County of San Francisco (1967)….

Whether an expectation of privacy counts as legitimate is less the result of any fixed set of rules than of “guideposts” stretching back to the Fourth Amendment’s beginnings. Id…. In recent decades, this Court has often confronted the challenge of adhering to those principles in the face of new technologies….[W]e held that the search of a cell phone incident to arrest could not proceed without a warrant (even though the search of a handbag could) because of the phone’s “vast quantities of personal information.” Riley [v.CA] (2014)… Most recently, in Carpenter, this Court held that accessing a form of cell-phone location information other than Location History is a Fourth Amendment search given individuals’ reasonable expectations of privacy.

…Contrary to the Government’s view, an individual has a legitimate expectation of privacy in the information Location History collects about his cell phone’s—meaning his own—movements. The police invade that expectation, and thus conduct a search, when they acquire that information, even though for only a limited period of time and even though via a third-party tech company.

….

The question presented in Carpenter was “whether the Government conducts a search under the Fourth Amendment when it accesses historical cell phone records that provide a comprehensive chronicle of the user’s past movements.”….The Court began its analysis by reviewing what it had said about a different way of tracking “physical location and movements”: the use of a GPS device to monitor a vehicle. Id. In United States v. Jones, [2012], five Justices had agreed that such tracking counts as a Fourth Amendment search because “individuals have a reasonable expectation of privacy in the whole of their physical movements.” … even though the movements occurred in public….“society’s expectation has been that law enforcement agents and others would not—and indeed, in the main, simply could not—secretly monitor and catalogue every single movement of an individual’s car.” Carpenter. A new technology should not transform what individuals had reasonably thought they could withhold from the Government.

It followed a fortiori, Carpenter held, that “[a]llowing government access to cell-site records contravenes” expectations of privacy. To an even greater degree than GPS monitoring, CSLI can provide a full “record of the holder’s whereabouts” and, with that, “an intimate window into a person’s life.” Ibid. People, after all, “regularly leave their vehicles,” but they “compulsively carry” their cell phones “all the time.” Ibid. A cell phone thus “tracks nearly exactly the movements of its owner”: It “faithfully follows” him not only through “public thoroughfares [but] into private residences, doctor’s offices, political headquarters, and other potentially revealing locales.” Ibid.

….

The Government, not much contesting any of the above, principally argues on a different ground: that accessing only a short amount of cell-phone location information… does not count as a Fourth Amendment search…In the Government’s view, a person has no reasonable expectation of privacy in “that short a time window” of location data, because his “short-term” movements will “reveal[] little about the details of [his] personal life.”….

But to begin, the Government is wrong about the incapacity of short-term location information to reveal private matters… “[E]ven short-term monitoring” of a person’s physical movements can provide “a wealth of detail about [his] familial, political, professional, religious, and sexual associations.”….

Still more fundamentally, we have never understood Fourth Amendment protections as kicking in only once an intrusion “goes too far.” … [T]he Amendment does not give agents a pass if their wiretap is of limited duration and thus less likely to intrude on private matters. Indeed, in our seminal wiretap case [Katz v. U.S. 1967], the police obtained only 18 minutes of recordings.

…What creates that concern is that the government can access all of a cell-phone user’s movements, in both public and private places—that it possesses a virtual panopticon with which to scrutinize its citizens’ activities. The sweep of the official invasion is not made less because the government, with the benefit of hindsight, can pinpoint exactly which few hours of movements it wants to review.

…The Government replies with an odd argument. It thinks that “tracking [someone] into a private residence”—yes, even for two hours—would “probably” be a search, but tells us not to worry because Chatrie did not go home. That approach, however, is foreign to the way the Fourth Amendment works. Whether something is a search does not depend on what it finds. An officer, after all, cannot know the fruits of a given surveillance in advance. The surveillance must be either a search or not regardless. The Government’s concession thus gives away its argument that, for purposes of the Fourth Amendment, two hours of cell-phone location data is not enough.

….

For all those reasons, we hold that police officers invade a cell-phone user’s reasonable expectation of privacy when they access his Location History. It does not matter if the time period scrutinized was only two hours. Nor does it matter that the materials obtained were handed over by a third-party tech company. When the government “accesses historical cell phone” location information—Location History as much as CSLI—it “conducts a search under the Fourth Amendment.”

That conclusion does not resolve this case, because the Fourth Amendment prohibits only searches that are “unreasonable.”….

When officers have obtained a warrant, as they did here, a search’s legality will thus depend on whether a magistrate has properly found probable cause to support a particularly described search….

….

…It is therefore now up to the Court of Appeals to decide whether, at each step of the search process, the warrant satisfied the Fourth Amendment’s requirements of particularity and probable cause.

….

In his famed and vindicated dissent, Justice Brandeis explained why a wiretap was a search, subject to Fourth Amendment requirements. Those who drafted the Amendment could not have imagined such a technology. But they understood, Justice Brandeis wrote, a matter of more transcendent importance: that Americans had “as against the Government, the right to be let alone” and that the Fourth Amendment must protect against “every unjustifiable intrusion by the Government upon the privacy of the individual, whatever the means employed.” [Olmstead v. U.S. 1928]… Today’s decision follows from the same judicial obligation, to guard against the same risk of undue encroachment. The Fourth Amendment applies, too, when officials tap into Google’s “database of physical location. [Carpenter] That database is new, but the principle covering it is not: That principle is instead the one our history has given. The Fourth Amendment must, as ever, protect against unjustified governmental intrusion on the privacy of the individual. For the reasons stated, we vacate the judgment of the Court of Appeals and remand the case for further proceedings consistent with this opinion.

It is so ordered.

Excerpted By Jackson Cook