> In a 2014 case out of a Virginia state court that seems to have set off the current debate, police obtained a search warrant to search a suspect’s home and to seize various items, including his smartphone that had TouchID enabled.
> The judge in that case drew a bright line: Under the Fifth Amendment, police could not force the suspect to communicate his passcode, but they could force him to use his fingerprint to unlock the device. The reason?
> Providing a fingerprint was “non-testimonial,” because it did not require the suspect to produce anything from his own mind. On the other hand, to give up your personal passcode is classically testimonial, since it comes from your head.
Which is why Apple put in a kill switch for Face ID (or Touch ID), if you hold down the power button (or power and volume down for newer iPhones) until the “Slide to Power Off” screen appears, the next unlock will require your passcode.
> The judge in that case drew a bright line: Under the Fifth Amendment, police could not force the suspect to communicate his passcode, but they could force him to use his fingerprint to unlock the device. The reason?
> Providing a fingerprint was “non-testimonial,” because it did not require the suspect to produce anything from his own mind. On the other hand, to give up your personal passcode is classically testimonial, since it comes from your head.
https://www.aclu.org/blog/privacy-technology/surveillance-te...