Can Police Make You Unlock Your iPhone with Your Face?

Facial recognition technology is touted as the newest security feature on some of the latest model smart phones, like Apple’s iPhone X. Just like its earlier Touch ID system, which authenticated the user through a sensor which read your fingerprint and compared it to the one you had registered in the phone’s security system, Apple’s new Face ID system uses a minuscule infrared sensor to scan your face, create a three-dimensional mathematical model of your face, and match it to the version stored in the phone’s memory.

But suppose a police officer stops you, for one reason or another, or a government investigator pays you a visit. A 2014 Supreme Court decision (Riley v. California) says 4th Amendment search provisions forbid searching a suspect’s cell phone without a warrant. Chief Justice Roberts, who wrote the decision, said cell phones are essentially mini-computers, and differentiated them from less private types of items that may generally be seized and searched. Lower courts have also reasoned that you can’t be required to give your cell phone’s password to a government searcher; that would violate their 5th Amendment right against self-incrimination.

Civil libertarians have warned facial recognition technology may threaten constitutional rights. Some point with alarm to its potential to facilitate stepped-up monitoring of citizens. For instance, during the 2015 riots in Baltimore following Freddie Gray’s death in police custody, city police reportedly used facial recognition technology on tapes of crowd scenes to try to identify persons with outstanding warrants.

Even increasing investigators’ access to suspect cell phones could raise constitutional issues. It would be easy to imagine a detective holding a smartphone equipped with Face ID or a similar facial recognition system up to its owner’s face while asking, “Is this your phone?” That could instantly unlock the device, opening it to investigators. But would that be lawful?

Some courts have allowed the government to make suspects supply a fingerprint needed to unlock a cell phone, if they have “reasonable suspicion” tying the suspect to a crime. It would likely be easier for investigators to unlock a suspect’s cell phone by getting a facial scan than by having to get a fingerprint (much less knowing which finger to use, since multiple tries with a different finger can shut down fingerprint authentication programs).

Facial recognition features on smart phones aren’t new; some Android phones have used the Face Unlock app since 2011. Some phone users point out that, on many phones, there may already be built-in methods for phone owners to disable fingerprint or facial recognition systems. I’ve already mentioned multiple wrong-fingered attempts to authenticate the phone user can shut down some facial ID systems, leaving having the password the only way to access the phone.

Other smart phones will shut down fingerprint or facial recognition features, thus requiring the password, if the phone is powered down, or the power/wake button is pressed five times in quick succession (in tweets, some computer users, perhaps with other interests, have taken to calling this the “cop button.”)

At present, there’s no clear answer to the question of investigators’ legal ability to use your face to access your cell phone, and there’s not likely to be one until definitive rulings begin to emerge from the courts.

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