"A new American Association for the Advancement of Science (AAAS) working group report on the quality of latent fingerprint analysis says that courtroom testimony and reports stating or even implying that fingerprints collected from a crime scene belong to a single person are indefensible and lack scientific foundation."
https://www.cmu.edu/dietrich/news/news-stories/2017/october/...
Wrong way to use fingerprints: "We have a crime and no suspects, but we have a fingerprint. We ran that through our database, and got a single match. That must be the person who left the print".
Right way to use fingerprints: "We have a crime and several suspects that we know were deeply involved in the matter that the crime was part of, but we don't know which were actually there during the crime. We also have this fingerprint left during the crime, and it matches exactly one of the suspects, which shows beyond a reasonably doubt he was there".
It's really no different from hair color, skin color, sex, height, weight, age, or DNA--the evidentiary value of a match on any of those depends on how that thing is distributed in the population that you can show by other means includes the correct person. The more you can narrow down that population, the better the evidentiary value.
Take sex for an extreme example. A woman reports that a man assaulted her in New York. There are a lot of men in New York, so if that's all you have to go on it is pretty worthless. But suppose an officer saw the attack, got a good enough look to see that the attacker is a man but nothing else, and saw that man run into a women's restroom to hide. The officer enters the restroom, and finds that it is occupied by two women and a man, and there is no way out of the restroom except the door the man entered by, which the officer had under observation continuously from the time the man entered to the time the officer entered and saw the three occupants.
Convicting that man for assault would be quite reasonable on the above evidence, even though it is largely based on the fact that he is male and the assailant was male. That's because other good evidence narrowed the population of possible assailants down to just three, and so if you can conclude that the assailant must be in that group, then the assailant being male does show that he was the assailant.
It's questionable whether the bathroom situation would satisfy the threshold, as it's based entirely on the testimony of an officer who somehow was able to ascertain gender but not (approximate) height, (approximate) weight or build, or race from his brief glimpse of the assailant. Moreover, it assumes the officer was correct about the gender of the assailant. Finally, it assumes that the officer was truthful in his statements. All in all, reasonable doubt exists at multiple levels and a good defense attorney only needs a single element of doubt.
>>This makes it scientifically baseless to claim that an analysis has enabled examiners to narrow the pool of sources to a single person.
While it doesn't narrow it down to a *single person, Fingerprints are still evidence. The litmus is to convince a jury of your peers.
It’s even worse with DNA which could have been transferred.
This is a perfect example of "begging the question"! Hopefully we can ammend the question with "we found a fingerprint at the scene that matches the suspect" and get that number down to 11/12.
A jurist is lawyer or otherwise an expert of law. You'd most likely get a panel of 10-12/12 jurists agreeing that it's possible the suspect wasn't there at the time the crime was committed.
You'd probably get a different answer if you asked a juror, but you still wouldn't get 12/12. Jurors are familiar with the concept of time. It's not even to prove that the suspect was there at all (especially if they have an explanation for why they were at the scene of the crime), the prosecution must establish they were specifically there at the time of the crime.
My guess is, they probably know but ignore it?
Somebody might also put on a fake license plate number matching your own on an car with the exact model as your own. Thus let's throw out witness accounts of car type/plate number.
If "beyond a reasonable doubt" is supposed to mean something, then it should mean something.
And by the way, eyewitness testimony is frequently really unreliable.
What's important is to lay out accurate odds for these systems, to which the fingerprinting folks don't always do. But a 5 point match on a fingerprint IS information even if it's not wholly conclusive.
We're actually pretty good at identifying uncertainty and certainty within the physical world. It's only when we get into very large or very small numbers that we start to lose the plot.