Wednesday, December 17, 2003

Federal Judge Limits Testimony from Bullet-Matching Expert

Faithful readers may remember last month's post reporting on scientific critiques of the forensic methods by which FBI experts compare the metallic composition of bullets to determine whether they came from the same batch.

A correspondent has now drawn to our attention a recent decision excluding FBI bullet-matching testimony in part. See United States v. Mikos, No. 02-cr-137 (N.D. Ill. Dec. 5, 2003) (Guzman, J.). The expert was permitted to testify that the bullets from the crime scene were indistinguishable, in chemical composition, from bullets recovered from the defendant's vehicle. But the testimony was excluded, for want of a sufficiently reliable scientific basis, insofar as the expert sought to opine on the likelihood that the bullets originated from the same manufacturing batch.
Fed. R. Evid. 702: If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise, if (1) the testimony is based upon sufficient facts or data, (2) the testimony is the product of reliable principles and methods, and (3) the witness has applied the principles and methods reliably to the facts of the case.