ForensisGroup Expert Witness Logo
(800) 555-5422

The Different Types of Experts & How They Can Assist Attorneys

Kat S. Hatziavramidis, Esq.

December 29, 2017


While it is common knowledge to many attorneys that different types of expert witnesses are available and frequently indispensable in litigation, familiarity with the details of such witnesses can be of great utility.

This article examines the many forms of guidance and assistance that experts can offer, in line with a helpful breakdown provided by the American Bar Association (ABA).

The intent of this article is to provide litigators with the knowledge and familiarity to know when and what type of expert witnesses can help accomplish and provide additional tools for success in court.


Attorneys are undoubtedly familiar with the fact that experts can be classified in two ways.

One way is to distinguish between the roles of consulting and testifying experts, while another relates to the type of expert, in terms of what area a witness specializes in, such as but not limited to:

  • Intellectual property (IP)
  • Social media
  • Medical professionals
  • Scientists

What may be of even greater benefit to attorneys is for them to know the uses that these different types of experts may have, as well as when such experts are most needed.

What follows is a discussion of those specifics.

1. Consulting Experts: The Many Talents They Offer

It is commonly understood that in general, “[C]onsulting experts are specialists…and have particular knowledge in their area of specialty… .

In general, the consulting expert is a person who is going to work to help the lawyers develop and advance a particular argument or strategy or tactical approach on behalf of their clients.

The consulting expert, then, is someone who is going to help the lawyers and the client promote their best interests in the case.

They are, in sum, advisors and advocates who probe all the strengths and weaknesses of the case on a consulting basis for the litigation team.” Weston Anson, “The Multiple Roles and Types of Experts,” American Bar Association, vol. 2, no. 10, May 2013.

In general, “[c]onsulting experts do not testify. Because a consulting expert will not appear in court, he or she need not worry about being faced with a Daubert challenge, or meeting the qualifications set down in Daubert and Frye and other expert standards used by a particular court.” Id.

The functions a consulting expert can perform are myriad and include:

(a) Educating Attorneys and Clients

A primary role that consultants play, which is integral in litigation, is to “educate litigators about the special issues of the case.” Id.

The reason that this function of a consulting expert is essential is because attorneys do not often have the specialized knowledge needed to speak to or fully understand what may be particularly at issue in a given lawsuit. See id.

The education function is one that can help attorneys even before they decide whether or not to take on a particular client or case, as consulting experts can weigh and explain what issues would come into play if litigation were to take place. See id.

As expressed by the American Bar Association:

“When a lawyer is considering whether to pursue a major case…or whether to launch a major litigation…, for example, they don’t usually have all the specialized knowledge necessary to make a decision as to how a case may best be presented from a …specialized knowledge point of view… .Therefore, the consulting expert is there to educate the attorneys and help them understand the alternatives available, both in terms of the business issues of the specific case as well as the alternative business or damages calculations that might be available. In an IP damages action, for example, the consulting expert can help the lawyer understand whether reasonable royalties are going to be easily established, whether disgorgement of profits is going to be a manageable solution, or whether alternative damages calculations make more sense.” Id.

(b) Evaluating Underlying Business Issues

In addition to helping educate attorneys as to whether to pursue litigation, what strategies and alternatives might exist, and what theories may hold water, consulting experts perform another important function.

According to the ABA, “Lawyers can use consulting experts to evaluate a specific case to determine whether the basic underlying business issues have merit.

For example, a client may claim that there has been consumer confusion caused by an infringing trademark, and a consulting expert can test the marketplace via random sampling, a survey, or other methodology to see if he or she can discover any actual confusion.

This sort of advance evaluation of the business issues in a case can be invaluable to the lawyer.” Id.

(c) Tests & Necessary Experiments

Because of their specialized knowledge, consulting expert witnesses have the unique ability to help litigators determine whether a theory is sound prior to litigation or discovery.

This can be accomplished by having a consulting expert “run tests in the field to see if the client’s claims are well-founded.” Id.

This, in turn, can help attorneys determine how far they wish to represent a particular client, whether a different theory is needed for a given case, and whether their own and/or opposing theories hold weight from a scientific or specialized viewpoint.

Such tests can prove invaluable at early stages of a case and may form the basis for a theory that is later advanced in court.

(d) Discovery & Development of a Case

In many views, discovery may be the most important phase of litigation, and it is certainly deemed a critical one by legal authorities. See, e.g., id. As the ABA notes, “[T]he consulting expert can play an important role in [the discovery] process by advising the lawyers on where discovery might be most effective.

For example, the consultants might construct a list of questions or requests for different types of information that would be most useful to a testifying expert in constructing a damages claim, or for another aspect of the case.

Similarly, they might point out to the lawyers other items of research that could be useful in developing the case.” Id.

(e) Locating Needed Experts

Because of their involvement in a specialized field, expert witnesses have a variety of colleagues and theories from their peers that they can evaluate, review, and assess the merits of.

In particular, consultants can be of particular utility in helping litigators to identify who, in a given field, would make a good testifying expert witness at trial. See id.

Well-respected members of a particular area of expertise typically have coworkers, friends, and fellow members of leading organizations in such fields, and the recommendation of a good consulting expert can help pave the way for an attorney to locate one who will be excellent as a testifying witness.

For example, a chemical engineer of prominence will often have publications and be familiar with the research and publications of others, be a fellow or member of a prominent group for top-tier specialists in the field, etc.

These connections can be invaluable to litigators in retaining other necessary expert witnesses.

(f) Dual Roles

It is also noteworthy that consulting experts can sometimes act in the capacity as testifying experts, as well, which is one more way in which they can prove valuable to attorneys. See, e.g., id.

One admonition the ABA proffers attorneys that should be considered is that “lawyers engaging a consulting expert must be cautious from the beginning that they maintain privilege and monitor communications with the consulting expert if they have any intention of possibly using the consulting expert in the future as a testifying expert.” Id.

2. Testifying Experts & Their Specialized Roles

While it is evident what the basic purpose of a testifying expert is, which is to provide specialized knowledge to factfinders that a lay witness cannot offer, there are different types of testifying experts and ways in which they can assist litigators in the quest for success.

The ABA divides testifying expert witnesses into two categories:

Those who have specialized knowledge to speak of Those who can attest to damages The distinction is important, as it reinforces the concept that every kind of expert, whether, consulting, testifying, or both, has something unique to offer attorneys and their clients.

(a) Providing Special Knowledge

The ABA explains that “the specific knowledge expert comes to the court with a background in a special area, such as intellectual property, medical or surgical techniques and malpractice, construction defects, etc.

On the other hand, the valuation and damages expert comes to the court with general knowledge of complex business and financial issues and analysis.” Id.

There are so many issues in modern litigation that require specialized knowledge, from patent infringement, to biochemical analyses, to environmental impact studies.

Experts with knowledge in specialized fields who can testify before a court are invaluable in not only advancing one attorney’s theory, but they can also help to debunk another’s.

Fortunately, once a litigator realizes what areas of expertise are needed, a host of experts exist, who can be retained and relied upon to credibly explain a given theory or claim.

(b) Damages Assistance

Absent expert testimony, it is nearly, if not actually, impossible to assess damages in most civil litigation.

Even within the field of damages experts, the ABA further subdivides such experts into two categories, “commodity valuation and damages experts, and the specialty valuation and damages experts.” Id.

The first category is somewhat general, and often includes people such as people with advanced financial training, like MBAs and CPAs. See id.

The second category is narrower, and the ABA explains the difference between the two as follows:

“The commodity side of this group of experts will have a general sense of how to use mechanical theories of valuation such that they are able in a gross sense to value a piece of real estate, a business, a medical device, or—at least in theory—a piece of intellectual property. On the other hand, the specialty valuation and damages expert will have a similar financial background but in addition, will have training specific to IP valuation.” Id.

Experts in both of these fields can be invaluable in helping courts assess damages and address the value of property, whether real, personal, or intellectual.


Clearly, expert witnesses play a variety of important roles in civil litigation. Whether acting as consultants, testifying, or performing both functions, knowing the many ways in which they can assist in a lawsuit can strengthen a case and improve the odds of success.

ForensisGroup Expert Witness Logo
301 N. Lake Ave. Suite 420
Pasadena, CA 91101-5119
Expert Witness Disciplines