What I find interesting is that there is overlap between knowledge and object that will surely be eroded by courts in the future. We are setting a precedent that a key and a fingerprint are equivalent, and fingerprint can unlock a password, which is knowledge. So what happens when the government authorizes the unlocking of passwords through replication of fingerprints? Would we agree that is permissible by the government's line of reasoning, i.e., rationalization? Well, what happens when brain wave reading technology is perfected and someone's brain wave patterns can be precisely read and thoughts read? Is that then also fair game to use technology to access the key, i.e., your brain waves, to gain access to your knowledge?
The argument that a fingerprint is like handing in a DNA sample or a physical key, which citizens can already be legally compelled to give to police. The significant point here, in my opinion, is that you can be legally compelled. I wonder if a request by a police officer is the same as being compelled "legally" or if it requires a court order if you refuse.