“Forensics is not limited to the sciences, though many forensic experts work in the sciences. Forensic experts may be retained to analyze almost any type of evidence and explains its significance to those working within the judicial system. A criminal defense lawyer may utilize forensic experts specializing in criminalistics, pathology, serology, photography, ballistics, odontology, botany, psychology, and toxicology, among others.”

It is the litigation lawyer’s job to lay the groundwork for the client’s case, to know the law, and to know how to present both the law and the facts to the judge and jury.

But a lawyer cannot be an expert in all fields, and it is for this reason that a lawyer must call upon experts who possess specialized knowledge to explain certain matters to the court. Although this aspect of representing a client might sound like a relatively easy task—considering how many experts in how many fields are out there—it is, in fact, an exercise fraught with perils both as to the outcome of the case and as to the ethical ramifications involved. We will examine the ethical and actual responsibility that the lawyer has for the hired expert witness.

The Critical Role of Experts

In one of the more celebrated criminal cases that resulted in an unexpected acquittal, the experts in the O.J. Simpson trial clashed for several days, with the prosecution’s star witness being grilled on the stand over the course of nine days. A forensic scientist from the Los Angeles Police Department who was responsible for collecting the blood and DNA evidence from the scene of the crime admitted under cross-examination that he had stored blood samples on the floor of a warm evidence truck for seven hours, had left a vial of Simpson’s blood unrefrigerated overnight and failed to collect blood stains from the gate of the crime scene until three weeks later.

As if that were not enough of a blow to the prosecution, the defense put on their own famed forensic scientist who underscored serious failures regarding blood collection and storage, and the rest, as they say, is history.

The Different Types of Experts

There is a difference between a consulting expert and a testifying expert, with the former basically being hired to educate the attorney regarding a complicated field that the attorney needs to understand and the latter being the expert who will educate the judge and jury. A consulting expert can be invaluable in helping the lawyer to understand a particular science or statistic and to help develop the proper approach to cross-examining an opposing expert witness.

Among the most common experts called upon in criminal cases are odontology (dental) experts and DNA experts, but increasingly, digital forensic experts are playing a role in cybersecurity litigation as well as in algorithm IP disputes.

Lawyer Liability for Expert Witnesses

But what happens if a lawyer puts on the witness stand a ‘weak’ expert who fails to persuade a jury or who cannot stand up to the opposing lawyer’s harsh cross-examination? Despite being an expert in one’s field, if the expert cannot express their opinions with confidence and think on their feet, then all of the expertise that they possess will be for naught as regards the successful outcome of the case. Although difficult to argue, such a scenario might possibly expose the lawyer to malpractice liability, the same as any other failure to properly prepare for his or her client’s case.

There is also the issue of a well-known expert having a ‘shelf life’; that is, after having testified in so many like-kind cases, a huge depository of transcripts becomes available, which, when reviewed by the opposition, opens the door to attack in the course of the next trial. Perhaps such an expert may no longer be the witness of choice when pressing a client’s case.

Ethics Regarding Expert Testimony

The ABA Model Rules (Model Rule 3.3–Candor Toward the Tribunal) expressly prohibit lawyers from knowingly making false statements to a court, and this prohibition applies as well when evidence is offered by a lawyer’s expert witness when the lawyer knows that the evidence is false. Furthermore, a lawyer’s failure to verify the veracity of testimony where multiple credible sources prove the testimony to be false may also result in a finding of unethical conduct and result in professional disciplinary action. In cases where a lawyer subsequently learns that expert testimony proffered was false, the lawyer has a duty to take remedial measures to correct such false testimony. There is a grey area, however, when a lawyer may be required, due to other, conflicting ethical considerations, to remain silent about an erroneous material fact.

The Ethics of Witness Fees

Various states have adopted rules (and formal opinions) regarding the payment of witness fees by lawyers. Such rules and regulations address the circumstances under which a lawyer can pay or compensate an expert witness, whether testifying at trial or at a deposition. Alabama, for example, has issued an opinion regarding expert witness fees that states that ‘an attorney may pay an expert witness a reasonable and customary fee for preparing and providing expert testimony, but the expert’s fee may not be contingent on the outcome of the proceeding.’

The penalties for violating expert witness fee rules—aside from disciplinary action—can be severe and can include having the expert’s testimony excluded or result in an adverse jury instruction that the contingency fee agreement can be considered in weighing the credibility of the expert. The exclusion of the expert’s testimony has been ordered by federal judges in Maryland and New Jersey. (Farmer v. Ramsay, 159 F.Supp. 2d 873 (D. Md. 2001); and, J&J Snack Foods v. Earthgrains Co., 220 F. Supp.2d 358 (D.N.J 2002).

Obtaining Client Consent

Yet another ethical aspect of engaging an expert witness is the issue of preserving client confidentiality. Virtually all jurisdictions (and indeed the ABA Model Rules) obligate the lawyer to preserve client confidentiality, and the sharing of case information with the expert witness, or, even worse, with the potential expert witness who ends up not being hired, can certainly expose the lawyer to professional responsibility liability in such circumstances. It is, therefore, crucial that the lawyer obtains from the client upfront and in writing authorization to share the case particulars with potential expert witnesses and, to obtain non-disclosure agreements from the experts, whether ultimately engaged or not.

As expert witnesses continue to play a pivotal role in the professional representation of a client before numerous tribunals, the lawyer must at all times be mindful of the possible pitfalls that exist when proceeding to utilize the services of an expert witness.

Executive Summary

The Issue

What is the lawyer’s ethical and practical responsibility when hiring an expert witness?

The Gravamen

Expert witnesses are critical components for the successful outcome of just about any litigation, but the lawyer must abide by both ethical and practical norms when hiring an expert.

The Path Forward

A lawyer must ensure that the testimony proffered by their expert witness serves the best interests of the client and does not expose the lawyer to professional responsibility violations.


Use of the Expert:

The lawyer must first determine what the function of the expert will be in terms of consulting, testifying, or both.

Client Consent:

Before discussing any aspect of a client’s case with an expert witness, the lawyer must obtain the client’s consent in writing to relate client confidences to a third party.

Fee Arrangements:

Know your state’s rules regarding expert witness fee arrangements in order to avoid the unpleasantness of sanctions and/or professional responsibility liability.

Verify the Expert’s Testimony:

Professional responsibility liability can also arise as a result of proffering false evidence before the court, and the lawyer must therefore take steps to confirm the veracity of the expert’s testimony before it is given.

Further readings:


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