When it comes to mobile, you pretty much have no privacy rights
As law enforcement continues to battle for access to mobile devices, police are being advised to not even look at a suspect's phone. The idea is that a phone that authenticates via facial recognition could fail to unlock for the officer repeatedly and then default to password/PIN.
This advice, contained in a series of vendor slides accessed by Motherboard, refers to iPhone's security lockout, which kicks in after five failed biometric authentication attempts. On the one hand, this could be an issue with FaceID. Unlike finger scans, it's hard to determine when one facial-recognition ends and a second begins. If someone looks at the phone and looks away and looks again, does that constitute two attempts? What if the person just looks at the phone for a relatively long time? Will the phone eventually conclude this should constitute more than one failed authentication attempt?