An article in Lingua Franca claims that fingerprinting is not a science. They make a good case that it isn’t.
In the article, a Canadian Mountie who is considered one of the foremost experts on fingerprinting claims that when the proper methods are used fingerprinting has an error rate of zero. Can anything with an error rate of zero really be considered a science?
What was really great about the court hearing described, is that the judge determined that only fingerprint experts could testify about the accuracy of fingerprinting. In other words, if you don’t believe in it, and if your livelihood doesn’t depend on it, then you’re not qualified to question it.
I watched a show last nite, I think it was State Police, where they scan your fingerprints and it automatically compares them to fingerprints in the database. Dunno if that’s science or not, but the bad guys better be careful whatever little crime they pull.
Of course this ignores the important question of “does it matter if it is or not?”
Is “gravity” science? Stuff is attracted to other stuff. To us, stuff falls toward the surface of the earth. And as long as the earth’s mass stays about where it is, that’s the way its going to be. The study of figuring that out, understanding the concept, that could be called science, but is the process(?) of gravity itself “science”? (And more importantly, does saying “that’s not science!” Make it go away or invalidate it in any way?)
I’m not sure what this is supposed to mean. I’d have to say that anything that can be studied to the point that one can make a prediction with confidence of being correct 100% of the time is exactly what science aspires to all the time. Let go a ball from your hand. Is it somehow not science to have determined the ball will ALWAYS go “down”?
Of course the court ruled that the only relevant testimony regarding accuracy of identification by fingerprinting was the testimony of an expert. Opinions from someone not expert in the science in question are almost always irrelevant, since they are not based on rational conclusions following study of the “science” involved. But I am sure there are oodles of experts in fingerprinting who can be called upon to testify in individual cases as to whether a given set of prints identify a given person; conflicting opinions can exist. Still, I haven’t heard of anyone seriously asserting that there are people with identical prints.
If the prosecution declares that the defendant leapt off a building, did three loop-de-loops, and crashed through a fifteenth story window to commit the crime, and he has an expert on antigravity and perpetual motion machines to testify that it’s possible, shouldn’t one question the validity of the “science” being presented?
“Things fall down” is a natural fact. Interpreting the plausibility of the above scenario is where science comes in. Another natural fact: Human beings have patterns of ridges on their fingertips which are (believed to be) unique to each individual. Now, a partial print lifted from a crime scene. The science is determining whose fingertips left that fingerprint.
Science in the courtroom is a sticky wicket. Science by its nature is supposed to be dispassionate, without bias, and subject to review by a body of competent researchers. That’s exactly the opposite of what goes in in a courtroom: “expert” witnesses, paid by one side or the other, quite possibly with dubious credentials, have a very limited amount of time to try to convice some laymen (be it the judge, or a jury) of one viewpoint or another, most likely through specious reasoning, emotional arguments, and appeals to authority which the laymen have no basis for evaluating.
If a so-called “expert” claims that any method has a zero rate of error, I’d definitely question the expert–though not necessarily the method. I’ve read that article, and a few others that are skeptical of fingerprinting in the past, and it seems that fingerprinting, just like any other science, has limits which are sometimes not acknowledged. Moreover, my impression (and I may be wrong) is that many fingerprint “experts” are not scientists, so that the process of peer review is somewhat lacking.
The article describes a hearing to determine if it concept of using fingerprints to identify a suspect as present at the scene is “science”, such that it is relevant evidence (a so-called Daubert hearing). The position of the defense against this evidence seems to boil down to the following: no one has studied to see if fingerprints are actually individually different in a way that allows one to establish identity through comparison of prints. Thus, such identification isn’t scientific, since one can’t know if the answer achieved by the practitioner is accurate.
This would be somewhat more substantial as an argument if it could be established that more than one individual CAN leave identical prints. I note that the defense didn’t present any such evidence, nor has anyone proffered such evidence.
Thus, the only attack on the “science” of fingerprint identification as a whole centers on the actual ability of the “expert” to correctly match prints. Even if we postulate that no two prints are identical, if the “expert” is unable to reduce the possibility of mis-identification to a small percentage, then the evidence would be irrelevant. Yet, when it came to producing evidence that the process wasn’t accurate, the defense managed only an eccentric iconoclast who testified that he “deplored” the lack of “objectivity” without producing any evidence that the procedure was consistently inaccurate, a director of an institute of applied microscopy who criticized the lack of prior statistical study of the underlying concept (but who failed to establish any evidence that the underlying concept was incorrect), and a person who has studied how it came to be that fingerprint evidence is accepted without such studies having been done. In short, there was no evidence that the methodology is inaccurate in general. In light of this fact, the determination of the court that the proposed expert opinions regarding the prints in question would be admitted was hardly surprising.
When someone manages to establish that either identical fingerprints are relatively common, or that it is impossible to accurately establish the identity of the maker of a print by comparison to a database of prints, then the issue can be questioned. Until then, this is much sound and fury about nothing.
And I might also point out that the FBI agent in question didn’t say that fingerprint matching in general has an error rate of zero, only that with perfect information in optimal conditions, the error-rate would be zero. In short, if you had a perfect print, you’d be able to correctly match it to another perfect print. Well, no duh.
I just noticed that my zero error rate statement didn’t come from the Canadian Mountie, but came from an FBI Scientists, my apologies to the Mounties and the good Canadian people.
If the FBI wishes to assert that there is a zero error rate under optimal conditions, and if we assume that no two partial fingerprints on the planet match, then that’s all well and good. But when was last time someone was convicted under optimal conditions?
It’s hard to ignore the fact that the FBI sent out fingerprints to 50 state agencies, and eleven of them failed to make the same match the FBI did. To me, that looks like a real world error rate of 12% (it’s more complicated than just 11/50). Is that a problem?
And wouldn’t it be nice if the FBI did more than simply assert that no partial fingerprints match in the world? Couldn’t they buy a Linux cluster and actually give it a try with their own database? Couldn’t someone?
If they’re not even willing to do that, then I have to conclude that fingerprinting is more conjecture than science.
Suppose that you were on a jury, and the only evidence to convict the defendant was a partial fingerprint match, would you convict?
If fingerprinting is an objective science, then I assume they are capable of measuring the differences between two sets of fingerprints. If you measure something, and then claim that you can measure it with 100% accuracy all the time, then that gives me pause.