For almost a century, fingerprinting has been the \gold standard"" for identifying people. But in the last decade, scientists have begun to question the technique and the aura of infallibility it has encountered in legal proceedings for so long.
Guest lecturer Michael Lynch, a professor of science and technology studies at Cornell University, said the principle of fingerprinting is sound, but its practice might be flawed. Yet because people have been so primed to accept certainty from fingerprint experts, it does not occur to jurors to question expert's testimony.
Since fingerprinting became popular in the late 1800s, examining fingerprints has become an exercise of matching a number of points, perhaps one to two dozen, between a known print and the print being tested. If all the points lined up, the examiner would declare a match.
""But the fingerprint the cops pick up might be latent, meaning it's smudged, very light or only a partial sample,"" Lynch said. ""So you could, and do, end up with false positives.""
Lynch added it is hard to quantify the frequency of false positives because there is no standard way to capture errors, but he cautioned that the sense of implicit trust creates a dangerous judicial environment.
""In any legal case, there is always other evidence besides fingerprints,"" he said. But the moment jurors believe that science is infallible, they tend to believe fingerprint evidence to the exclusion of everything else, even if the fingerprint expert's analysis was flawed.
DNA testing raises similar concerns, but Lynch said the O.J. Simpson trial actually underscored an important scientific point.
Though the science of DNA testing is also sound, Simpson's defense lawyers successfully argued the testing in his case was flawed because investigators mishandled the evidence. Lynch said jurors who are aware of this will be less likely to simply believe ""the distinguished graying individual on the stand who says, 'My opinion is based on my many years of experience.'""
Joan Fujimura, UW-Madison professor of sociology, said this is a topic that demands to be discussed.
""It's important for us to consider how the courts use scientific evidence. This is serious-people's freedoms could be at stake,"" Fujimura said.
Hanna Grol-Prokopczyk, a graduate student in sociology, agreed.
""Science and technology can be very theoretical, but [Lynch] showed us how to apply them to something as important as murder trials,"" she said.
