The definition of privacy seems to be continually evolving on America’s legal system.  Knowledge is protected, but physical attributes are not.  Are we heading toward the need for multi-factor authentication for personal devices already under our control?  Does the end outweigh the means in this situation?  I have a feeling this debate is far from over.

https://nakedsecurity.sophos.com/2016/10/18/feds-got-search-warrant-demanding-anyones-fingerprints-to-open-phones/