For what it's worth, both fingerprints and iris scans can be done in such a way as to differentiate "live" from "dead". In a fingerprint scanner, you can potentially look for heat, for a pulse, or even use those nifty optical blood oxygen sensors. Likewise, an iris scanner can look for evidence of a pulse and can even flash a light or something to detect evidence of photosensitivity. The issue, as always, is cost.

(And, worse yet, biometrics of all sorts are non-revocable. If for whatever reason it turns out that you and somebody else share a biometric, maybe because you're twins, or maybe just a result of a bad turn of luck, then there's absolutely nothing you can do to fix it.)

The big brotherly aspects of this smell awfully like something out of a dystopian cyberpunk novel. Really, it's not about changing the presumption of innocence as much as it's a wholesale elimination of any "right of privacy" that we might have ever had. Probably the only place that Joe Sixpack truly understands the value of privacy is when it comes to spam (whether phone, mail, or whatnot). Similarly, if I get mistakenly flagged in some database, perhaps as a result of identity theft or whatnot, it's easy to imagine falling into a Kafkaesque nightmare of trying to straighten things out again.