The chance of false match on fingerprints is actually quite small, but we don't know how they are using the tool. In the US, a fingerprint match has to be verified independently by two certified fingerprint examiners before some action is taken. I don't know how they are using it in Afghanistan, but from what I have heard it *is* a screening tool. If they get a match, they just detain the person until they can figure out out what the deal is. I suspect the rate of false positives is not all that high, otherwise the tool would be useless for checkpoints.