Like fingerprints, every person's irises are different; not even both irises of the same person are the same. Fingerprints can take a while to verify through state and national databases, but an iris scan, which uses more data points for biometric identification, can come up with a match within a few seconds. Those are the pros, if you're a security expert. But they're minuses if your concern is privacy. Fingerprints, by their very nature, are an active identification metric; you have to touch something to imprint them. But iris scans are passive — you just walk past a security camera (or, as in "Minority Report," billboards in the mall) and the person controlling the scanner can spot your identity within seconds.