Why Face ID won’t give you the legal protection of a passcode

In the short time since Apple announced its Face ID feature for the iPhone X, we’ve seen a lot of questions about its security compared to a fingerprint or passcode. For example, if you’re arrested, can a police officer just point your phone at your face and unlock it?
Apple has some technical features that might make this harder. The iPhone X isn’t supposed to unlock if your eyes are closed, for example, and since iOS 11 reportedly lets you disable Touch ID on the fly, you mig