A forensic expert witness is a type of expert witness who would provide expert forensic testimony within a trial. Forensic expert testimony would be testimony grounded within and concerning the field of forensic science, which, in turn, is a branch of science which is specifically designed to assist with answering important questions that might arise within a given trial.
A forensic expert witness thus might be a specialist in any of a number of fields of forensic science, including forensic anthropology, forensic archaeology, forensic chemistry, forensic dactyloscopy, and forensic computer science. The expert testimony of a forensic expert witness would be meant to provide an analysis of particular pieces of evidence and information which would then support the argument of the side which brought in the forensic expert witness.
Thus, the expert testimony of a forensic expert witness might be differentiated from the expert testimony of another type of expert by the fact that the forensic expert witness would likely be providing expert testimony directly on evidence from the case in question, whereas an expert witness providing expert testimony might provide more generalized expert testimony concerning a question which might be significant to the case in question, but without commenting directly upon evidence of the current case.
A commonly known form of forensic expert witness is a scientist who performed an examination of a human skeleton so as to provide important evidence for a criminal trial. This scientist would then be called as a forensic expert witness to provide expert testimony regarding the skeleton.