Re: How in the name of sweet beJesis is this legal?
This is probably the key "who do you match it against and why".
If you have a database of people who are convicted drunk drivers banned from driving and you match active drivers against it then that is direct crime detection - OK?. Now if you have a database of convicted pickpockets and you use cctv footage at a festival is that ok?
Now change the word from convicted to suspected - still OK? etc.
So we need clear rules who and why you match it against.
We need to define rules of engagement when a match is made. First the match must be manually verified by a competent officer, then an agreed process to approach the possible suspect and verify their identity in a polite and acceptable way.
Now denying it works now is pointless, the evidence is that it will work soon and as it evolves it will become a major part of police work, we just need to manage the genie as it comes out of the bottle.