GIZMAG ran a page about the future of identifying people by their somewhat individual odors. I say 'somewhat', because the article notes that the accuracy of the scent ID is currently only about 85%.
http://www.gizmag.com/body-odor-biometric-identification/30718/?utm_source=Gizmag+Subscribers&utm_campaign=bf5ff1e0ed-UA-2235360-4&utm_medium=email&utm_term=0_65b67362bd-bf5ff1e0ed-76704577
Though not mentioned in the article, the 15% margin of error compares to visual ID that can only tell hair, eye, skin color, & height, & little else. Yet, it does seem like it will lead to more erosion of privacy.

hmy: I hate to think of future ID cards having a scratch & sniff element on them, then the cop who has pulled you over wants to use a probe to sniff your rear end, to verify that you are the person listed on the card.
