If the Police Freeze Your Phone, Can They Force You to Unlock It With Your Face?
(Read Time: 4 Minutes)
By Ollie Coull
Imagine you’re walking down the street, and the police stop you. They suspect you of a crime and seize your phone. They know everything they need to crack the case is locked behind your lock screen. One officer holds the phone up to your face, the sensors flash, and boom—the phone clicks open.
Did they just break the law, or did you just accidentally give up your legal rights without saying a word?
This isn't a scene from a sci-fi movie. It's a massive, real-world legal battleground happening right now. Depending on whether you live in the United States or the United Kingdom, the rules about whether the police can force your phone open are wildly different—and honestly, pretty sneaky.
Step 1: The Privacy Hurdle (Warrants and Probable Cause)
Before we even talk about your face or your passcode, there is a massive legal wall the police have to clear. They cannot just grab your phone and start looking through it on a whim.
In the United States, the supreme law of digital privacy comes from a landmark Supreme Court case called Riley v. California. The court ruled that modern cellphones are essentially minicomputers containing the most intimate details of your life. Because of that, the Fourth Amendment requires police to get a search warrant signed by a judge before they can search a seized phone. To get that warrant, police must establish probable cause—meaning they have to present concrete facts to a judge showing it is highly likely that evidence of a specific crime is hiding inside that particular phone. If they search it without a warrant, the evidence gets completely thrown out of court.
In the United Kingdom, things operate under the Police and Criminal Evidence Act 1984 (PACE). Under Section 19 of PACE, if an officer has lawfully stopped or arrested you, they have the power to seize your phone if they reasonably believe it contains evidence of an offense. But seizing the phone and searching the phone are two different steps. To actually dive deep into your data, they have to follow strict legal guidance and document a clear link between your device and the crime.
The US Rules on Unlocking: The Fifth Amendment vs. Biometrics
Once the police have the legal right to hold your phone, how do they get past the lock screen?
In the US, everything comes down to the Fifth Amendment to the Constitution. It says you have the right to remain silent and that you cannot be forced to be a witness against yourself. But the US Supreme Court draws a huge line between two types of evidence:
Testimonial Evidence: Things you know or say. The contents of your brain.
Physical Evidence: What your body physically is.
The police cannot force you to give up a typed passcode or text password because that requires you to dig into your brain, which is protected. But they can force you to give a fingerprint or stand in a lineup because those are just physical characteristics.
This leaves Face ID in a massive gray area. Some US courts think your face is just physical skin, so police can hold the phone up to you without your permission. Other courts think that is terrifying and argue that using your face to decrypt a phone forces you to admit ownership of the data inside, which should be protected under the Fifth Amendment.
The UK Rules on Unlocking: The "Hand It Over or Go to Jail" Notice
If you look across the ocean at the United Kingdom, they don't have a written constitution like the US, and their rules are way more direct.
If a UK police officer stops you on the street, they cannot physically assault you or force your face or thumb onto a phone screen to unlock it. There is no law that allows them to use physical force to make you use biometrics.
However, the UK has a secret weapon called Section 49 of the Regulation of Investigatory Powers Act 2000 (RIPA). If the police have legally seized your phone, they can hand you a formal, written notice. This notice legally demands that you hand over your PIN, your password, or unlock the device right then and there.
If you refuse to comply with that paper notice? You are committing a completely separate criminal offense. Under Section 53 of the same law, you can be thrown in prison for up to 2 years just for keeping your phone locked—or up to 5 years if the case involves national security. Saying "I forgot it" doesn't easily work either; the burden of proof is on you to prove you actually forgot it.
Arguments For and Against
The Argument For Police Forced-Unlock: Law enforcement in both countries argues that smartphones are just modern filing cabinets. If they have a legal warrant to search your things, you shouldn't be allowed to hide evidence behind a digital wall. If they can use a physical key to open your house, why not your face to open your phone?
The Argument Against: Privacy advocates argue that your phone is not just a filing cabinet—it contains your entire life, location history, and private thoughts. Letting police bypass your rights just because you chose a convenient feature like Face ID means the law is failing to keep up with modern technology.
The Bottom Line
Think of it this way: your lock screen is a heavy vault door. The Fourth Amendment and PACE dictate whether the police have the legal right to walk up to the vault door in the first place. The Fifth Amendment and RIPA dictate whether they can force you to hand over the key to unlock it.
Right now, technology is moving way faster than the law. In the US, the courts are totally split on whether forcing your face to unlock a phone violates the Constitution. In the UK, they won't force your face to the glass, but they will give you a piece of paper that threatens jail time if you don't type the PIN yourself.
No matter where you are, if you want maximum privacy before a police encounter, the trick is simple: lock your phone down so it forces an alphanumeric passcode instead of biometrics.
References (APA 7)
Police and Criminal Evidence Act 1984, c. 60. https://www.legislation.gov.uk/ukpga/1984/60/contents
Policing.uk. (2024). Can police force you to unlock your phone?https://policing.uk/know-your-rights/can-police-force-you-to-unlock-your-phone
Regulation of Investigatory Powers Act 2000, c. 23. https://www.legislation.gov.uk/ukpga/2000/23/contents
Riley v. California, 573 U.S. 373 (2014).
Schmerber v. California, 384 U.S. 757 (1966).
State v. Diamond, 890 N.W.2d 143 (Minn. 2017).
U.S. Const. amend. IV.
U.S. Const. amend. V.
United States v. Barrera, 692 F. Supp. 3d 11 (E.D.N.Y. 2023).
United States v. Hubbell, 530 U.S. 27 (2000).
United States v. Wade, 388 U.S. 218 (1967).
