Consulting vs. Testifying Expert Witnesses

Deciding whether to hire an expert for a legal case often brings to mind witnesses testifying in court, but there are also valuable non-testifying experts who play crucial roles behind the scenes.

Attorney meeting with expert witness

ByZach Barreto


Published on June 17, 2024

Attorney meeting with expert witness

When first deciding whether to hire an expert for a legal case, thoughts of a witness testifying in a courtroom and offering testimony in their field of expertise to the jury might be the first thought that is conjured. However, not all experts are retained for the purposes of testifying. Non-testifying experts, by comparison, also referred to as consulting experts, are those who do not testify by are nonetheless utilized throughout the litigation process. The versatility of non-testifying experts, coupled with relatively favorable discovery rules governing the disclosure of expert witnesses and their work product, make them a valuable tool in the litigation arsenal.

What is a Testifying Expert?

A testifying expert plays a huge role in the outcome of a case. If testifying at trial, these witnesses offer their expertise to explain complex factual issues which in turn, assist the trier of fact in rendering a verdict. An experienced expert who is able to skillfully testify as to crucial issues of fact can be the ultimate deciding factor in the case’s outcome. Aside from possessing the requisite educational background and experience, a testifying expert should also have strong communication skills and the ability to break down scientific or technical language so that a layperson may understand it. 

As such, a testifying expert’s job does not begin only once they are under oath in a courtroom or at a deposition. A good testifying expert will be involved in the case as early as possible, in order to review all necessary materials and craft a strong case theory.

Disclosure Rules for Testifying Experts

A typical requirement of a testifying expert is to draft a written report of their proposed testimony which must be provided to opposing counsel. Under Rule 26(a)(2)(B) of the Federal Rules of Civil Procedure (as well as a majority of states that follow a similar rule), a testifying expert must include the following in their report:

  1. All opinions the witness will testify to, as well as the basis and reasons for the opinions held.
  2. The data or facts the witness considered when forming their opinion.
  3. Disclosure of any exhibits the expert witness intends to use to summarize or support his or her opinions.
  4. The qualifications of the witness, including a list of all publications the expert witness has authored in the past ten years.
  5. A list of cases the expert witness provided deposition testimony or trial testimony during the past four years.
  6. A statement regarding the expert witness’s compensation for the review and evaluation of the evidence, as well as their testimony in the case.

These disclosures must be made at least 90 days before the expert’s testimony (and for rebuttal witnesses, within 30 days of the opposing party’s disclosure). After the reports are disclosed, the expert may be deposed by the opposing party.

What is a Consulting Expert?

In comparison, a consulting expert is retained for the purposes of assisting with the litigation, including at trial, but does not offer testimony. A consulting expert can assist with crafting a case strategy and can review materials in preparation for trial. They can also assist in the hiring process of a testifying expert, as they may be in a better position to vet the background and experience of someone in their field.

Disclosure Rules for Consulting Experts

Unlike testifying experts, under Rule 26(b)(4)(D), experts that are retained for these purposes are ordinarily not subject to interrogatories or depositions, absent exceptional circumstances. Whether a non-testifying expert’s identity needs to be disclosed in federal court is split between the circuits. Although the work product of a testifying expert may be discoverable, non-testifying experts typically enjoy consulting expert privilege protections in this regard.

What is a Dual Role Expert?

In certain cases, an expert may take on a dual role as both a testifying and consulting expert witness. Although this strategy may present beneficial cost savings, it runs the risk of exposing the expert to disclosure requirements they otherwise would not have been under if they only acted as a consultant.

Legal and Procedural Considerations

The differences in disclosure requirements between consulting and testifying experts under Rule 26 of the Federal Rules of Civil Procedure have obvious implications for case preparation and strategy.

Although work product is generally protected, Rule 26’s written report requirement makes certain communications between the witness and attorney discoverable, such as communications related to compensation, as well as any information provided by the attorney on which the expert based their opinion, including assumptions, thereby potentially chipping away at work product protections.

As a result, an attorney’s decision to share their opinions or assumptions may vary depending upon the type of expert with which they are engaging. 

Strategic Uses in Litigation

In order not to disclose more than necessary, it is important to definitively determine whether your expert will be utilized as a testifying witness. Once you designate an expert as a witness and disclose their report, you cannot “un-ring” that bell, even if you later determine the expert works better as a consultant. As such, it might be a safer strategy to treat all potential experts as consultants until you are sure that you will need their testimony at trial.

Selecting the Right Expert

Whether you are searching for a non-testifying or testifying expert – or both – you will want to research the expert’s credentials, background, and experience. Expert witness disclosure is a crucial aspect to consider during this process.

Expert Institute’s Expert Search Service does the work for you by carefully vetting every expert in our network of over 3 million experts across various industries, disciplines, and subject matter relevant to your specific case. Each expert undergoes a stringent vetting process, ensuring an impeccable track record and exceptional performance during deposition and cross-examination. Our search service will help you engage actively practicing professionals who match all your requirements.

Overall, there are significant discovery advantages to retaining non-testifying experts, although their identities may be disclosed and their work product subject to discovery in certain circumstances. By hiring both non-testifying and testifying experts, they each play a distinctive role in maximizing the likelihood of a favorable outcome at trial.

About the author

Zach Barreto

Zach Barreto

Zach Barreto is a distinguished professional in the legal industry, currently serving as the Senior Vice President of Research at the Expert Institute. With a deep understanding of a broad range of legal practice areas, Zach's expertise encompasses personal injury, medical malpractice, mass torts, defective products, and many other sectors. His skills are particularly evident in handling complex litigation matters, including high-profile cases like the Opioids litigation, NFL Concussion Litigation, California Wildfires, 3M earplugs, Elmiron, Transvaginal Mesh, NFL Concussion Litigation, Roundup, Camp Lejeune, Hernia Mesh, IVC filters, Paraquat, Paragard, Talcum Powder, Zantac, and many others.

Under his leadership, the Expert Institute’s research team has expanded impressively from a single member to a robust team of 100 professionals over the last decade. This growth reflects his ability to navigate the intricate and demanding landscape of legal research and expert recruitment effectively. Zach has been instrumental in working on nationally significant litigation matters, including cases involving pharmaceuticals, medical devices, toxic chemical exposure, and wrongful death, among others.

At the Expert Institute, Zach is responsible for managing all aspects of the research department and developing strategic institutional relationships. He plays a key role in equipping attorneys for success through expert consulting, case management, strategic research, and expert due diligence provided by the Institute’s cloud-based legal services platform, Expert iQ.

Educationally, Zach holds a Bachelor's degree in Political Science and European History from Vanderbilt University.

background image

Subscribe to our newsletter

Join our newsletter to stay up to date on legal news, insights and product updates from Expert Institute.