Police generally need a warrant to search your phone. See what Riley, Carpenter and the June 2026 Chatrie decision say, and where the border and passcode questions stay unsettled.
Police search your phone legally in a few situations, but as a rule they need a warrant. The Supreme Court said so in 2014 in Riley v. California, and it has extended the same privacy logic to location records in Carpenter (2018) and, most recently, to Google location history in Chatrie (June 29, 2026). The big exceptions are consent, true emergencies, and the border, where courts have given officers more room. This post covers US federal law, and notes where states and circuits differ.
Each section takes one situation, such as an arrest, a traffic stop, an airport, or a request to unlock the screen, and explains what the main cases say.
After an arrest: the Riley rule
Before 2014, police could search items on a person during an arrest. In Riley v. California, decided June 25, 2014, the Supreme Court refused to stretch that rule to cell phone data. Phones, it reasoned, are not weapons, and once a phone is in police hands the owner cannot delete anything from it. It also stressed how much a modern phone holds, often including cloud data, which makes a search far more intrusive than looking through a wallet.
The Court’s instruction to police on what to do before searching a seized phone was short: “get a warrant.” That does not mean police cannot take the phone. They can seize and hold it while seeking a warrant. They just cannot browse it without one, absent an exception.
One exception survived. The exigent circumstances doctrine still applies, so emergencies such as an imminent bomb threat or a child abduction may justify a search without a warrant, judged on the facts of each case.
Location data: Carpenter and Chatrie
The phone in your pocket also leaves a trail with your carrier and with app companies. In Carpenter v. United States, decided June 22, 2018, the Court held that getting historical cell-site location records from a wireless carrier is a Fourth Amendment search, and that the government generally needs a warrant. The case involved 127 days of records and 12,898 location points. The Court said the older third-party doctrine, under which information you share with a business loses protection, does not stretch to this data. It also said its decision was narrow: it did not cover real-time location data, tower dumps, or security cameras.
The newest chapter is Chatrie v. United States, decided June 29, 2026, which concerns a geofence warrant, a request for data on every device in an area during a time window. Justice Kagan’s majority held that accessing Google Location History is a Fourth Amendment search, because people have a reasonable expectation of privacy in that data and do not truly share it with Google in the ordinary sense. The Court rejected the argument that a short two-hour window takes the search outside the Constitution.
It did not decide that geofence warrants are invalid. The Fourth Circuit had held no search occurred, so it never examined the warrant itself; the Supreme Court vacated and remanded, leaving open whether each step of the multi-step warrant met probable-cause and particularity requirements. It also left the good-faith exception for the lower court. The docket lists a concurrence by Justice Jackson joined by Justice Sotomayor and a separate concurrence by Justice Gorsuch, with dissents from Justice Alito and Justice Barrett.
Traffic stops, consent and plain requests
Most real-world phone searches are not about the Constitution so much as about consent. If an officer asks “mind if I look at your phone?” and you say yes, a court will usually treat the search as valid. You can say no. Saying no is not, by itself, a reason for police to take further action, and a warrant rather than a polite request is what they need. I did not research cases on how courts judge whether consent was voluntary, so I will not attempt to say when consent is invalid.
At the border: the big exception
This is where the answer changes. Courts have long allowed searches at the border without a warrant, and the rules for electronic devices are unsettled. A reference summary describes the main decisions:
| Case and court | Standard described |
|---|---|
| Cotterman, Ninth Circuit (2013) | Quick searches need no suspicion; forensic examination requires reasonable suspicion |
| Kolsuz, Fourth Circuit (2018) | Forensic searches of visitors’ devices need individualized suspicion |
| Touset, Eleventh Circuit (2018) | Forensic searches need no suspicion |
| Vergara, Eleventh Circuit (2018) | No warrant or probable cause ever required; Riley does not apply |
| Alisigwe, Second Circuit (2026) | No suspicion required to search property at the border; declined to extend Riley |
That page says the Supreme Court has not resolved the question, and that CBP policy requires reasonable suspicion for advanced, forensic searches. I could not open CBP’s own policy page, so the policy point rests on that secondary summary, as does the 2026 Second Circuit ruling. Verify both before relying on them. The practical upshot is that location matters: the same search of the same phone may be treated differently depending on which circuit an airport sits in.
Can police make you unlock it?
This is a different question from whether they can search. Even with a warrant, forcing you to reveal a passcode raises the Fifth Amendment problem of compelled testimony. A reference page on key disclosure summarizes the older cases. Courts that apply the “foregone conclusion” idea reason that if the government already knows what is on a device, producing the password adds nothing. A Colorado federal district court ordered a woman to decrypt her laptop in 2012, while the Eleventh Circuit held the same year that forced decryption of a laptop violated the Fifth Amendment. In 2019 the Pennsylvania Supreme Court held that a suspect could not be compelled to reveal a password, under that state’s law.
That page does not address fingerprints or face unlock, and I did not find a verified source on those, so I make no claim about them. Courts have not spoken with one voice, and the answer can turn on whether you are asked to say something (a passcode) or to do something (press a finger). If you are in this situation, the right move is to ask for a lawyer.
A quick reference by situation
| Situation | General rule | Main authority |
|---|---|---|
| Phone seized at an arrest | Warrant needed to search the data, unless an emergency | Riley (2014) |
| Historical carrier location records | Warrant generally needed | Carpenter (2018) |
| Google Location History via geofence | Access is a search; warrant validity left to lower court | Chatrie (2026) |
| You say yes to a search | Usually valid if consent is voluntary | General principle, not researched here |
| International border | Looser; standard varies by circuit | Circuit decisions above |
| Forced passcode disclosure | Unsettled; Fifth Amendment arguments | Lower-court cases above |
Reading the table, notice how much rests on lower-court decisions. The Supreme Court has set the floor on searching a phone’s contents and on location data. It has not set one national rule for the border or for compelled unlocking, which is why the same facts can come out differently in different courts.
Why the Court treats phones differently
A thread runs through Riley, Carpenter and Chatrie: a phone is not like the objects the old rules were written for. In Riley, the Court pointed to the volume and variety of what phones hold. In Carpenter, it stressed that location records are detailed and retrospective, and that carrying a phone is practically necessary in modern life. In Chatrie, the majority found location history more precise than the cell-site records at issue in Carpenter.
The effect is that old doctrines, such as search incident to arrest and the third-party rule, get applied narrowly to digital data. Expect the next fights to concern new categories: tower dumps and real-time location, which Carpenter expressly left open, and the validity of individual steps in geofence warrants, which Chatrie sent back to the Fourth Circuit. Lawyers following the remand will be watching how that court treats probable cause and particularity, and whether it reaches the good-faith exception.
What you can do to protect yourself
- Know the difference between asking and ordering. A consent request is a request. A warrant is a court order and should be shown to you.
- Do not volunteer a passcode. Whether you can be forced to give it is unsettled, as above.
- Say clearly that you do not consent to a search. That preserves your objection for a later court.
- Treat the border differently. Travelers may want to consider what is on a device before an international trip, since the border rules are the least protective.
- Do not physically resist. Challenge the search later through a lawyer.
These tips are general practical points, not guidance for any particular situation.
Related questions
Can police search my phone during a traffic stop?
Not without a warrant, consent or an emergency, based on Riley. Riley dealt with arrests, so a stop that does not end in an arrest is an even weaker basis for a search.
Can police get my location without telling me?
They generally need a warrant for historical cell-site records under Carpenter, and the Court’s 2026 ruling in Chatrie treats Google Location History as protected too. Real-time location data was left open by Carpenter.
What is a geofence warrant?
A request for data on devices present in an area during a specific time. Chatrie says reaching that data is a search, but did not decide when such a warrant is valid.
Do state rules differ?
Yes. State constitutions and statutes can add protection beyond the federal floor, as in the Pennsylvania compelled-password ruling. Check your own state.
This is general information, not legal advice.
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