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Law 101: Legal Guide for the Forensic Expert

Use of Hypothetical Questions

Use of hypothetical questions is still a valid method of examination. In preparation for direct examination, the expert and counsel may prepare a list of hypothetical questions that encompasses all facts that have been established. The technique on cross-examination is to insert into a hypothetical question facts which could lead the expert to reach a conclusion opposite to that tendered on direct examination.

Attacking the expert by using an authoritative publication is one of the most effective devices in the cross-examiner's toolkit. Federal Rule of Evidence 803(18) states that the expert does not have to recognize a learned treatise as authoritative to be cross-examined about it. At least in the federal courts, if any expert witness testifies that a particular treatise is authoritative, the expert, as a testifying witness, may be examined about it. This rule makes the expert potentially responsible for mastering vast amounts of information.

A direct attack on the expert's position is difficult to undertake, yet the effort will be made in a proper case. On occasion, the expert may be tempted to maintain a position of absolute certainty, even in the face of overwhelming contradictions. That dogged adherence to a position can destroy the expert's credibility.

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Date Created: August 7, 2023