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Law 101: Legal Guide for the Forensic Expert

Generating Additional Discovery Requests

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National Institute of Justice (NIJ) (see reuse policy).

Additional discovery requests may be generated by reviewing Federal Rules of Evidence (FRE) 702703, and 705 in preparation for a challenge to the admissibility of scientific evidence.

FRE Rule 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.

FRE Rule 703: The facts or data in the particular case upon which an expert bases an opinion or inference may be those perceived by or made known to the expert at or before the hearing. If of a type reasonably relied upon by experts in the particular field in forming opinions or inferences upon the subject, the facts or data need not be admissible in evidence in order for the opinion or inference to be admitted. Facts or data that are otherwise inadmissible shall not be disclosed to the jury by the proponent of the opinion or inference unless the court determines that their probative value in assisting the jury to evaluate the expert's opinion substantially outweighs their prejudicial effect.

FRE Rule 705: The expert may testify in terms of opinion or inference and give reasons therefore without first testifying to the underlying facts or data, unless the court requires otherwise. The expert may in any event be required to disclose the underlying facts or data on cross-examination.

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