But for what, precisely, would they be used? Judge Caprice Cosper in Houston has suggested repeatedly that deployment of these personal fingerprint scanners would make police more comfortable with using their cite-and-release authority for certain Class B misdemeanors because they could be sure at the scene who they were letting go. That's supposedly what's happening in England. According to BBC, "A suspect's fingerprint can be taken on the device and almost instantly checked against the police database. If a match is discovered, further relevant investigations can be made by an officer at the station. An NPIA spokesman said data from the scan is only used to check a match and is not retained."
Here's what I don't understand, and perhaps some informed reader can help me out: I've sat through presentations from Texas DPS fingerprint examiners who insisted that, unlike on TV (and apparently England) where fingerprints are matched in seconds by a computer, in Texas a real live human subjectively, laboriously compares prints for possible matches, and a second fingerprint examiner must verify it before a match can be declared. When a new set of fingerprints comes in, they go onto the stack until an actual person gets around to looking for a match, and that person generally has a backlog.
So if deployed in Texas, as Grits understands it these personal fingerprint examiners wouldn't let officers ID an individual on the street, they would only gather data which could be used later for whatever purpose. (In the UK, by contrast, the data "is not retained"). I can see where it might be useful for investigators interviewing suspects, witnesses, etc., for future reference. But as long as fingerprints are matched manually, these personal fingerprint scanners wouldn't let Texas police ID individuals at the scene. They'll still have to find out who they are the old fashioned way: By asking them.