The way that current laws are written in the US has meannt that the “keys” to biometric passwords like facescans, fingerprints, and other similar technologies are treated like traditional searches for which police can easily obtain warrants. Alphanumeric passwords, however, are treated as “testimonial” evidence, meaning that defendants have Fifth Amendment protections from self-incrimination. So, although protected by significantly more advanced technology, it is often easier for police to access these devices than those protected by simpler passcode technology.
Source: The Newest Password Technology Is Making Your Phone Easier for Police to Search – Nextgov
