When Apple announced in 2013 that its next iPhone would include a fingerprint reader, it touted the feature as a leap forward in security. Many people don’t set up a passcode on their phones, Apple SVP Phil Schiller said at the keynote event where the Touch ID sensor was unveiled, but making security easier and faster might convince more users to protect their phones. (Of course, Apple wasn’t the first to stuff a fingerprint reader into a flagship smartphone, but the iPhone’s Touch ID took the feature mainstream.)
The system itself proved quite secure—scanned fingerprints are stored, encrypted, and processed locally rather than being sent to Apple for verification—but the widespread use of fingerprint data to unlock iPhones worried some experts. One of the biggest questions that hung over the transition was legal rather than technical: How might a fingerprint-secured iPhone be treated in a court of law?
The question went unanswered for a year, until a Virginia judge ruled in 2014 that police can force users to unlock their smartphones with their fingerprints. But until this February, when a federal judge in Los Angeles signed a search warrant that required a woman to use her fingerprint to unlock her iPhone, it didn’t appear that any federal law-enforcement agency had ever used that power.