Riley v. Cal. United States
The Supreme Court ruled that police generally may not search the digital contents of a cell phone taken from someone they've arrested without first getting a warrant.
The decision recognizes that smartphones hold vast amounts of deeply personal information, and it draws a firm line between searching a person's physical belongings during an arrest and searching the data on their phone.
“Our answer to the question of what police must do before searching a cell phone seized incident to an arrest is accordingly simple— get a warrant.”
The Court's bottom-line rule for cell phone searches during an arrest.
How it got here: A California trial court and the California Court of Appeal upheld Riley's phone search and conviction; a federal district court upheld Wurie's search, but the First Circuit reversed and vacated his convictions.
The Case in Depth
What happened
David Riley was pulled over for expired tags, and a search after his arrest turned up a phone whose contents linked him to gang activity and an earlier shooting. In a separate case, Brima Wurie was arrested after an apparent drug sale, and police used call-log data from his seized flip phone to track down and search his apartment, where they found drugs and a gun.
The question before the Court
Can police search the digital contents of someone's cell phone without a warrant just because they've arrested that person?
The Court's answer
No — the Court ruled that police generally must get a warrant before searching the digital contents of a cell phone taken from someone they've arrested. The old rule allowing warrantless searches of items on an arrestee's body developed to protect officers from weapons and to stop the destruction of evidence, but phone data poses neither danger once the phone itself is secured, and modern phones hold far more sensitive personal information than anything typically carried in a pocket or wallet.
The Court rejected several proposed middle-ground rules — like allowing searches only for evidence of the arrest crime, or only of information with a pre-digital equivalent — as unworkable or too permissive. Police can still search a phone without a warrant when a genuine emergency exists, such as an imminent bombing threat, but routine arrests no longer justify digging through a phone's data on the spot.
Curious how the Court got there? See the step-by-step legal reasoning →
Why it matters
Anyone arrested — for a traffic stop, a drug sale, or anything else — can no longer have their phone's photos, messages, browsing history, or apps searched on the spot by police without a warrant. Officers must generally take the extra step of getting judicial approval first, though urgent emergencies can still justify an immediate search.
What changes now
Riley's case goes back to the California courts for further proceedings consistent with the warrant requirement the Court just announced, while Wurie's conviction stays vacated as the First Circuit ordered. Going forward, police nationwide generally need a warrant before searching an arrestee's cell phone, though they may still rely on the existing emergency-circumstances exception when facing a genuine, immediate threat like an imminent bombing or a missing child.
What this does not decide
The Court did not rule that phone data is immune from search altogether — only that a warrant is generally required first. It also left open how the emergency-circumstances exception applies case by case, and did not decide whether searching information stored remotely in the cloud, rather than on the device, is treated the same way.
Concurrences and dissents
Concurrence — Justice Alito
Justice Alito agreed that officers generally need a warrant to search a cell phone's contents, but he doubted that the traditional search-incident-to-arrest rule was ever based mainly on officer safety and evidence preservation, pointing instead to historical sources that focused on gathering evidence. He also urged that legislatures, not courts, are better positioned to craft detailed rules balancing privacy and law enforcement needs for modern devices, much as Congress did for electronic surveillance after Katz v. United States.
How the Court got there
The legal reasoning, step by step
- The Court applied its long-standing test for whether a type of search falls outside the warrant requirement: weighing how much the search intrudes on privacy against how much it serves legitimate government interests, rather than relying on guidance from the Constitution's framing era.
- It traced the search-incident-to-arrest exception through three prior cases: Chimel v. California, which limited such searches to protecting officer safety and preventing evidence destruction; United States v. Robinson, which applied that rule to physical items on an arrestee's body without case-by-case analysis; and Arizona v. Gant, which added a narrower vehicle-specific rule.
- The Court found that neither of Chimel's justifications applies well to phone data: the data itself cannot be used as a weapon, and once a phone is physically secured, the risk of the arrestee destroying evidence largely disappears, with remaining evidence-loss concerns like remote wiping being speculative and addressable through other means like disconnecting the phone or invoking the emergency exception for urgent situations.
- Turning to the privacy side of the balance, the Court reasoned that cell phones differ qualitatively and quantitatively from wallets or address books because of their immense storage capacity, their ability to combine many types of sensitive records in one place, and their near-universal presence in people's daily lives.
- The Court rejected three proposed compromise rules — importing the vehicle-search standard from Gant, limiting searches to information relevant to the crime or officer safety, and allowing searches of anything with a pre-digital physical counterpart — finding each either unworkable or providing no real limit on searches.
- Having concluded that the government interests underlying the search-incident-to-arrest exception do not justify warrantless cell phone searches while the privacy interests at stake are substantial, the Court held that officers must generally obtain a warrant before searching a phone's digital contents, though case-specific emergency circumstances remain available.
Doctrinal impact
Cases affected by this decision
Limits United States v. Robinson (414 U. S. 218)
The Court declined to extend Robinson's categorical rule allowing searches of physical items to digital data on cell phones.
Reaffirms Chimel v. California (395 U. S. 752)
The Court relied on Chimel's officer-safety and evidence-preservation rationale to test whether cell phone searches fit within it.
Distinguishes Arizona v. Gant (556 U. S. 332)
The Court found Gant's vehicle-search standard unsuited to cell phones because it would impose no real limit there.