Forensic Expert Witness Qualified to Testify in Criminal Case


Ballistics Expert WitnessThis case involves a man who was charged with murder in aid of racketeering through the use of a firearm. At trial, the Government attempted to use an expert witness in forensic science to testify that it was his opinion “to a reasonable degree of ballistic certainty” that a bullet recovered from the victim’s body and shell casings recovered from two related crime scenes came from firearms linked to the man. The man sought to exclude the testimony of the forensic expert witness on the grounds that it did not meet the requirements for admissibility under Rule 702 of the Federal Rules of Evidence.

Question(s) For Expert Witness

  • Does ballistics testimony from a forensic expert witness meet the requirement of being sufficiently reliable so that it is admissible in a criminal case under Rule 702 of the Federal Rules of Evidence?

Expert Witness Response

In general, ballistics testimony presented by forensic expert witnesses has in the past been held to be admissible in courts across the United States. Recently, however, courts have held that ballistics testimony presented by forensic expert witnesses is not based on sufficient rigor, and so it cannot be presented in court as scientific. This new holding is based on the fact that there is no reliable scientific methodology that can allow a forensic expert witness who is a ballistics analyst to testify that a casing and a particular firearm are a “match” to an absolute certainty, or to an arbitrary degree of statistical certainty. In addition, ballistics opinions by forensic expert witnesses are highly subjective. This means that a forensic expert witness’s assessment of the quality and quantity of resulting tool marks (i.e. the marks imparted from the gun to the bullet and/or casing) and the decision of what does or what does not constitute a “match” comes down to a subjective determination based on the expert’s intuition and experience. Even though this is the case, the gun manufacturing process causes differences between any two guns that, while small, can still be detected by use of ballistics techniques. Because the unique characteristics of each gun are to a great degree copied onto some or all bullets and casings fired from that gun, ballistics technology has gained significant empirical support. Since the ballistics expert in this case can probably testify with some certainty about whether the firearm “match” was more likely than not, he can probably present admissible testimony under Rule 702.

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