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Use of Expert Testimony (From Basic Course for Prosecutors XII, V 2, P 95-126, 1987 - See NCJ-112901)

NCJ Number
M S Ross
Date Published
32 pages
This monograph addresses five key questions prosecutors must ask themselves to determine the proper handling of expert testimony on direct examination and cross-examination.
Prosecutors must first decide if they want expert testimony. The general rule is to use it only if it is essential for proving the case. In some circumstances, it may undermine what is an otherwise strong case. In determining whether expert testimony is legally permitted in a case, the prosecutor must examine the controlling test enunciated by numerous courts. This test requires that the issues covered in the testimony be beyond the knowledge possessed by a typical juror and that it be based on a reasonable degree of scientific certainty. After deciding that expert testimony can and will be used, the prosecutor must then decide how to prepare for the direct examination of the expert witness. Elements in preparation are stipulation regarding the witness' expertise, the impropriety of testimony on 'an ultimate issue,' the presentation of the testimony by the standard of 'a reasonable degree of scientific certainty,' the parameters of the testimony, and the bases for the expert's opinion. Other issues discussed are preparation for and essentials of the cross-examination of an adverse expert witness and principles relating to the introduction of physical evidence at trial.