25,005 research outputs found

    The Reliable Application of Fingerprint Evidence

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    In November 2017, a state appellate court did something almost unprecedented: It held that a trial judge made an error by admitting testimony on latent fingerprinting. In State v. McPhaul, the North Carolina appellate panel found error in admitting expert testimony, based on the lack of evidence that the expert reliably reached conclusions about the fingerprint evidence. The panel did not reverse the defendant\u27s conviction, however, finding the error to be harmless. The ruling has broader significance for as-applied challenges to the forensic testimony commonly used in criminal cases, in which judges have often not carefully examined reliability either for many forensic methods in general, or how they are applied in a given case. Many forensic techniques rely on the subjective judgment of an expert, who may not be able to fully explain how they concluded that a fingerprint, ballistics, or other types of pattern evidence is a match, except to cite to their own judgment and experience. In this essay, I describe the scientific status of fingerprint evidence, the facts and the judicial reasoning in McPhaul, and the implications of the decision. This sleeper ruling should awaken interest in the reliable application of forensic methods in individual cases

    DeepMasterPrints: Generating MasterPrints for Dictionary Attacks via Latent Variable Evolution

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    Recent research has demonstrated the vulnerability of fingerprint recognition systems to dictionary attacks based on MasterPrints. MasterPrints are real or synthetic fingerprints that can fortuitously match with a large number of fingerprints thereby undermining the security afforded by fingerprint systems. Previous work by Roy et al. generated synthetic MasterPrints at the feature-level. In this work we generate complete image-level MasterPrints known as DeepMasterPrints, whose attack accuracy is found to be much superior than that of previous methods. The proposed method, referred to as Latent Variable Evolution, is based on training a Generative Adversarial Network on a set of real fingerprint images. Stochastic search in the form of the Covariance Matrix Adaptation Evolution Strategy is then used to search for latent input variables to the generator network that can maximize the number of impostor matches as assessed by a fingerprint recognizer. Experiments convey the efficacy of the proposed method in generating DeepMasterPrints. The underlying method is likely to have broad applications in fingerprint security as well as fingerprint synthesis.Comment: 8 pages; added new verification systems and diagrams. Accepted to conference Biometrics: Theory, Applications, and Systems 201

    The Proficiency of Experts

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    Expert evidence plays a crucial role in civil and criminal litigation. Changes in the rules concerning expert admissibility, following the Supreme Court\u27s Daubert ruling, strengthened judicial review of the reliability and the validity of an expert\u27s methods. Judges and scholars, however, have neglected the threshold question for expert evidence: whether a person should be qualified as an expert in the first place. Judges traditionally focus on credentials or experience when qualifying experts without regard to whether those criteria are good proxies for true expertise. We argue that credentials and experience are often poor proxies for proficiency. Qualification of an expert presumes that the witness can perform in a particular domain with a proficiency that non-experts cannot achieve, yet many experts cannot provide empirical evidence that they do in fact perform at high levels of proficiency. To demonstrate the importance ofproficiency data, we collect and analyze two decades of proficiency testing of latent fingerprint examiners. In this important domain, we found surprisingly high rates of false positive identifications for the period 1995 to 2016. These data would qualify the claims of many fingerprint examiners regarding their near infallibility, but unfortunately, judges do not seek out such information. We survey the federal and state case law and show how judges typically accept expert credentials as a proxy for proficiency in lieu of direct proof of proficiency. Indeed, judges often reject parties\u27 attempts to obtain and introduce at trial empirical data on an expert\u27s actual proficiency. We argue that any expert who purports to give falsifiable opinions can be subjected to proficiency testing and that proficiency testing is the only objective means of assessing the accuracy and reliability ofexperts who rely on subjective judgments to formulate their opinions (so-called black-box experts ). Judges should use proficiency data to make expert qualification decisions when the data is available, should demand proof of proficiency before qualifying black-box experts, and should admit at trial proficiency data for any qualified expert. We seek to revitalize the standard for qualifying experts: expertise should equal proficiency

    Neural Networks for Fingerprint Recognition

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    After collecting a data base of fingerprint images, we design a neural network algorithm for fingerprint recognition. When presented with a pair of fingerprint images, the algorithm outputs an estimate of the probability that the two images originate from the same finger. In one experiment, the neural network is trained using a few hundred pairs of images and its performance is subsequently tested using several thousand pairs of images originated from a subset of the database corresponding to 20 individuals. The error rate currently achieved is less than 0.5%. Additional results, extensions, and possible applications are also briefly discussed

    Fixing Rule 702: The PCAST Report and Steps to Ensure the Reliability of Forensic Feature-Comparison Methods in the Criminal Courts

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    In response to PCAST’s recommendation, the Standing Advisory Committee on Evidence Rules convened a meeting on forensic expert testimony, Daubert, and Rule 702 on October 27, 2017, at Boston College Law School to inform itself about the issues.22 The meeting included presentations by twenty-six speakers (including myself) and discussion among the attendees. The purpose of this Article is to summarize aspects of the PCAST report relevant to its recommendation to the Standing Advisory Committee on Evidence Rules and to propose a path forward with respect to Rule 702
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