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Law 101: Legal Guide for the Forensic Expert

Ethical Violations

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

Some issues covered in previous modules describe ethical violations by the forensic witness. However, other ethical violations that may occur in forensic testimony of experts can be avoided — or used for cross-examination.

Providing outright false data. The cross-examination process is charged with the obligation of exposing falsified information, reports, records or other basic data. This requires the most meticulous preparation and investigation by cross-examining counsel, well before the time a fallacious expert takes the witness stand.

Not conducting an investigation. The approach of counsel is to look at records, filed reports, bench notes and standard protocol to establish that purported investigations were, in fact, performed.

Altering data. Resorting to the original documentation is the most effective way of discovering alterations; alterations consist of changes to data or documents that are not supported by analysis. Obliterations through correction fluids, erasures or digital tampering may be exposed by original document examination. Proper corrections (e.g., in the medical field and for ASCLD-LAB accreditation) require that a single line be drawn through an erroneous record, with the author's initials. Anything short of that is suggestive of document tampering.

Giving false testimony. On occasion, a witness will falsely testify on the basis of information either erroneously provided or carelessly gathered. False testimony rarely arises from an intentional desire on the part of the witness to support the claim of the sponsoring party with no regard for the truth or falsity of the statement. Here, the weight of cross-examination provides strength for the opposition.

Intentionally ignoring available data. This oversight can occur through counsel, a sponsoring party who does not reveal to the expert all of the requisite data, or by the expert who turns a professional cold shoulder on salient facts. In either case, a cross-examination may expose such blind-siding.

Recanting prior contra positions. Often an expert has testified to or written concerning a particular proposition. The cross-examiner who uncovers a prior contra-position in another related or similar case has in hand the tools to expose the expert in a potential contradiction. The expert should be mindful of what is said on the witness stand, understanding that those statements may come back to haunt the witness. The expert that has a legitimate reason for changing a position should be certain that the reasons for doing so can be sufficiently documented.

Accepting assignments beyond one's competency. This area of cross-examination applies, not to admissibility of expert testimony, but rather to the weight given to an expert's testimony. An expert clearly out of his or her depth should be exposed by careful cross-examination indicating that the assignment was simply beyond the witness's experience and capability.

Allowing improper attorney influence. Communication between the expert and attorney is the best way to uncover efforts by the sponsoring counsel to influence the expert's opinions. Normally, such correspondence is not privileged in any way, except if it is a pure attorney work-product and was not relied on by the expert in forming a professional opinion. In the event the witness has relied in whole or in part on the attorney statement, such information is proper for production and examination.

Reaching conclusions before research is conducted or completed.  One of the opportunities for cross-examining attorneys is to have an expert jump to a conclusion before any study or research has been done to buttress or support the conclusion. Through cross-examination and meticulous file analysis, it may be possible to uncover the fact that an expert opinion or conclusion was reached before adequate research was done. This issue pertains to the weight assigned to the testimony and not to its admissibility. If the circumstances are sufficiently egregious, the witness's entire testimony may be stricken.

Allowing conflicts of interest. Conflicts of interest can provide a legal basis for expert challenge and a court-ordered disqualification of an expert witness. In the event materials were made available to an expert on the other side of an assignment before the current assignment, there is case law that prohibits an expert from testifying in the current case. Aside from circumstances that justify disqualification, a conflict of interest situation presents a viable area of cross-examination that may apply to the weight assigned to the testimony and may impinge on the expert's integrity.

Using fraudulent credentials. This involves the task of checking the details of an expert's curriculum vitae and personal résumé. Although experts are admonished to maintain a careful recitation of historic accomplishments, some tend to exaggerate their own credentials. By verifying the data contained in the resume before trial, it is possible to expose outright falsehoods. Falsehoods in the résumé/curriculum vitae can lead the fact-finder to the conclusion that there are falsehoods in the report as well.

Overstating conclusions.  This can occur when an expert uses terms to indicate that the results are more probative or useful than are actually supported by the data (e.g., stating that a match occurred with microscopic hair comparison testing). Although the defendant may not be excluded as a potential source, this is far less meaningful than stating a match which jurors would take to mean it is the defendant's hair.

Giving confusing or misleading testimony.  This is similar to overstating, but it could also mean failing to explain technical processes so jurors can understand and put results in context.

See: "Asserting the Expert's Rights as a Witness"

"Ethical Violations and Examples of Abuses by Experts"

"Addressing and Countering Claims of 'Junk Science'"

"Ethical Conduct and Discovery"

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