Comment No such thing as a match (Score 1) 86
Systems like facial scanners, fingerprint scanners, DNA, etc. do not and cannot tell you that a scan matches one person out of many.
What they do tell you is at what confidence level you can reject the null hypothesis that a random persons' random scan matches a specific persons data.
So in a scenario where you have a identity specified separately from the scan, like fingerprint unlock the account on a computer or the electronic passport gate line at an airport, it is at least statistically plausible to make a functioning system.
However, if you are trying to select from identities based on scans, given enough scans and identities something will match by dumb luck, possibly multiple matches.
There's also the question of whether the system would be allowed to not reject the null hypothesis or would the demand come to change the confidence level until something could be declared a "match".