Assuming they're using this tech to avoid bloody murder and not to track down the guy riding his bicycle too fast (for example) or the gypo who stole a few chickens (allegedly at the top of Interpol's wanted list before Al Q grabbed the limelight), I still think it's better to check a persons credentials and be wrong some of the time than to have had an opportunity to catch a terrorist and missed it for fear of having a complaint filed.
However, they need to have a think about how they go about apprehending people when there's a chance of error.
Assuming they're using this tech to avoid bloody murder and not to track down the guy riding his bicycle too fast (for example) or the gypo who stole a few chickens (allegedly at the top of Interpol's wanted list before Al Q grabbed the limelight), I still think it's better to check a persons credentials and be wrong some of the time than to have had an opportunity to catch a terrorist and missed it for fear of having a complaint filed. However, they need to have a think about how they go about apprehending people when there's a chance of error.