Biometrics and the Fifth: Can Fingerprints Be Compelled to Unlock Devices?

Biometrics and the Fifth: Can Fingerprints Be Compelled to Unlock Devices?

The Fifth Amendment says that no one can be “compelled in any criminal case to be a witness against himself.” This means you can’t be forced to give evidence that could incriminate you. But what about being forced to use your fingerprint or face to unlock a phone or computer? Can the police make you do that if they have a warrant? This issue has caused a big debate in the courts recently.

On one hand, your fingerprint or face scan seems like physical evidence, not testimony. The police can already take your fingerprints or DNA when they arrest you. But unlocking a phone shows that it’s yours and could reveal private information inside. Is that more like testimony? There are good arguments on both sides.

The Rise of Biometrics

Using biometrics – like fingerprints, face scans, or iris scans – to unlock phones and computers has become super common over the last 10 years. In 2013, Apple introduced Touch ID on the iPhone 5S, which let you unlock your phone with your fingerprint. Then in 2017, they released Face ID on the iPhone X, using advanced cameras and sensors to scan your face.

Now most new phones and laptops have biometric sensors built-in. People like them because they’re faster and easier than typing in passcodes. Companies promote biometrics as more secure too, since your fingerprint or face can’t be guessed or hacked like a passcode can.

Why Phones Contain Sensitive Information

The other big change is how much personal information is now kept on our phones and computers compared to 10 years ago. They contain our emails, texts, photos, internet history, location data, and much more. The Supreme Court has called cell phones “such a pervasive and insistent part of daily life” that carrying one is indispensable to participation in modern society.

So our devices hold a ton of private info about our lives. That’s why the police need a warrant to search them, just like they’d need one to search your home. The courts have said we have a strong privacy interest in the contents of our devices.

The Split Between Courts

So what happens when the police have a valid warrant to search your phone, but it’s locked with a fingerprint or face scan? Some courts have said they can compel you to unlock it with biometrics. But other courts have said this violates the Fifth Amendment right against self-incrimination.

For example, a federal court in Illinois said that unlocking a phone with biometrics is like giving a DNA sample or fingerprint, which has been allowed. It’s physical evidence, not testimony. But a California court said compelled biometrics are like giving a passcode, which is protected by the Fifth Amendment.

Arguments for Allowing Compelled Biometrics

Here are some of the main arguments made by courts that allow compelled biometrics:

  • Biometrics like fingerprints are physical characteristics, not testimony.
  • The police can already take fingerprints and DNA samples from suspects.
  • Unlocking a device doesn’t reveal the contents of your mind.
  • You’re just being compelled to unlock the device, not reveal incriminating evidence.

In U.S. v. Barrall, the court said biometric unlocking is “more akin to surrendering a key than revealing a passcode.” You’re not revealing your thoughts, just using your fingerprint to unlock the device. Other courts have agreed with this reasoning.

Arguments Against Allowed Compelled Biometrics

Here are some arguments made by courts that don’t allow compelled biometrics:

  • It forces you to implicitly testify that the device is yours.
  • It gives access to potentially incriminating information.
  • Fingerprints can reveal more than just physical data.
  • The Fifth Amendment should adapt to new technologies like biometrics.

In Commonwealth v. Baust, the court said compelled biometrics violate the Fifth Amendment privilege against self-incrimination. Unlocking a device communicates ownership and authenticates access to private information. It’s like testimony, even if it seems physical.

Where the Supreme Court Comes In

This issue will likely end up at the Supreme Court eventually. The justices will have to decide whether biometric unlocking should be treated more like physical evidence or testimony protected by the Fifth Amendment. It could go either way based on prior rulings.

In 1966, the Supreme Court said being compelled to provide fingerprints is not protected by the Fifth Amendment because fingerprints are physical, not testimonial. But technology has changed a lot since then. Unlocking a phone with biometrics reveals much more information than just fingerprints.

The Supreme Court has also said the Fifth Amendment privilege can evolve along with new technologies. So the justices may see biometrics as something now deserving of Fifth Amendment protection, even if fingerprints on their own didn’t in the past.

Balancing Privacy and Security

This issue puts important values in tension – individuals’ privacy versus law enforcement’s ability to investigate crimes. The Supreme Court will have to balance these interests when deciding if compelled biometrics violate the Fifth Amendment. It’s a very tricky issue with reasonable arguments on both sides.

On one hand, we want the police to be able to effectively gather evidence when they have a valid warrant. But we also want to protect individuals’ privacy and not force them to incriminate themselves. Where should the line be drawn for new technologies like biometrics? There are good-faith arguments on both sides.

In the end, the Supreme Court will likely aim for a nuanced compromise between these values. They may allow compelled biometrics in some cases but not others, depending on the totality of the circumstances. Either way, this debate highlights how applying old constitutional principles to new technologies often raises difficult questions without easy answers.


Here are some references used as sources for this article: