Also known as: skilled witness · expert witness · expert witnesses
Written by attorneys · grounded in primary & secondary sources — see below
A witness qualified by specialized knowledge, skill, experience, training, or education to provide opinion testimony that assists the trier of fact. The witness may base opinions on facts or data reasonably relied upon in the field even if those facts are not independently admissible. In criminal cases the witness may not state an opinion on whether the defendant possessed a mental state constituting an element of the offense or a defense.
Scott Summers faces federal fraud charges. The government calls an accounting expert who reviewed ledgers and then states that Summers must have formed the intent to mislead investors. The court strikes the mental-state conclusion because only the jury may decide whether the defendant possessed the required mens rea element.
Samantha Stone is prosecuted for assault. The state's DNA analyst testifies that a profile generated by a non-testifying lab matches the crime-scene sample and explains her independent opinion without offering the report for its truth. The court admits the testimony because the profile served only as the foundation for the analyst's own conclusion.
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Stephen Shaw and Solstice Ventures dispute complex valuation issues in a contract case. The judge issues an order to show cause why a neutral financial expert should not be appointed and later selects an agreed-upon appraiser who consents to serve. The appointed expert then supplies an independent valuation that both sides may cross-examine.
Sydney Santos sues after a product fails. On cross-examination the defense confronts the plaintiff's engineering expert with a passage from a recognized industry manual stating that certain stress levels are normal. The expert acknowledges the manual as authoritative, and the court permits the statement to be read to the jury.
Solomon Silver claims a tire defect caused his accident. The defense offers a tire-failure analyst whose methodology relies on visual inspection and experience rather than published standards. The court evaluates whether the approach is reliable for the particular facts and admits the testimony after finding it rests on sufficient specialized knowledge.
Steven Silva offers a novel blood-analysis technique in a criminal trial. The prosecution objects that the method has not gained general acceptance in the scientific community. The court applies the prevailing standard and excludes the testimony because the technique lacks the required recognition among experts in the field.
Yes. When a party intends to elicit opinion testimony based on scientific, technical, or other specialized knowledge from an employee, that witness must be identified in the expert disclosures even if the employee also possesses personal knowledge of the facts.
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The party must disclose the subject matter of the expected expert testimony and provide a summary of the facts and opinions the physician is expected to state. A full written report is not required unless the physician was specially retained for litigation.
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No. Rule 704(b) prohibits an expert from stating an opinion about whether the defendant did or did not have a mental state or condition that constitutes an element of the crime charged or of a defense.
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On a party's motion or on its own initiative the court may order the parties to show cause why an expert should not be appointed, may request nominations, and may appoint any qualified person who consents to serve.
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…"gatekeeping" determination limited to "scientific" knowledge. Daubert pointed out that Federal Rules 702 and 703 grant expert witnesses testimonial latitude unavailable to other witnesses on the "assumption that the expert's opinion will have a reliable basis in the knowledge and experience of his discipline." Id. , at 592…