Commercial Damages Expert Witnesses in Missouri Litigation

This guide explains why damages experts matter, the kinds of experts who do this work, the admissibility standard Missouri adopted in 2017 under RSMo § 490.065 (a Daubert-style reliability test), the common valuation and lost-profits methods, how experts are disclosed and deposed, and how the other side moves to exclude an opinion it considers speculative or unreliable.

Why damages experts matter in Missouri business litigation

Winning on liability is hollow if you cannot prove damages: a jury that finds a breach but no credible proof of loss may award little or nothing. The expert turns a business injury into a defensible dollar figure the law will accept.

Missouri's governing principle is reasonable certainty. Lost profits and similar damages need not be calculated with mathematical exactness, but they must be proven with reasonable certainty rather than left to speculation or conjecture — meaning the expert must tie the number to financial records, market data, and a recognized methodology.

• Proving lost profits. When a breach, fraud, or tortious interference cost a business sales, an expert reconstructs what the company would have earned absent the wrong.
• Business valuation. When the dispute is about the worth of a company or an ownership interest — a buy-sell fight, a dissociated partner — an appraiser establishes value.
• Diminished value. When conduct reduced (but did not destroy) a business's or asset's value, an expert measures the decline.
• Rebutting the other side's number. A rebuttal expert attacks the opposing calculation's assumptions, data, and method, often shrinking a large demand.

A recurring Missouri wrinkle: lost profits for an established business with a track record are far easier to prove than for a brand-new or unestablished business, which has no operating history to anchor the projection and must rely on comparable-business or market evidence.

The kinds of commercial damages experts

Different injuries call for different specialists, and complex cases often use several.

• Forensic accountants. The most common damages experts. They analyze financial statements, tax returns, and accounting records to reconstruct lost profits and quantify losses with documentary support.
• Economists. Used for broader analyses — market conditions, causation, discount rates, and present-value calculations — especially where the loss stream extends years out.
• Business appraisers / valuation experts. Credentialed professionals who determine the fair market value of a company or an ownership interest.
• Industry experts. Specialists in a trade or market who supply the real-world assumptions a calculation rests on — typical margins, pricing, or whether a projection is realistic.

The right expert needs both a sound method and credible qualifications to survive the admissibility test below.

The admissibility standard: RSMo § 490.065 and Daubert

Before a jury ever hears a damages number, the expert's testimony must clear an admissibility gate. In 2017, Missouri amended RSMo § 490.065 to adopt the federal Daubert standard for expert testimony in most civil cases, replacing its older, more permissive approach. The statute now mirrors Federal Rule of Evidence 702.

Under this framework, the trial judge acts as a gatekeeper, admitting expert testimony only if three things hold:

• Qualifications. The witness is qualified by knowledge, skill, experience, training, or education.
• Reliable methodology. The opinion rests on sufficient facts or data and is the product of reliable principles and methods, reliably applied.
• Fit to the facts. The testimony actually helps the trier of fact and is relevant to the specific dispute — it must "fit" the case.

The Daubert reliability factors

Several non-exclusive factors a court may weigh when judging reliability originate in Daubert v. Merrell Dow Pharmaceuticals and FRE 702, and Missouri courts apply them under RSMo § 490.065:

• Whether the theory or technique can be (and has been) tested;
• Whether it has been subject to peer review and publication;
• The known or potential rate of error; and
• Whether the method enjoys general acceptance in the relevant professional community.

For a damages expert, this means using recognized financial and valuation methods — not a one-off formula invented for the case — applied to real data with defensible assumptions. An opinion that skips the company's records or uses an idiosyncratic method is most vulnerable to exclusion.

Common damages and valuation methods

Which method fits depends on the injury and the available data.

Lost-profits methods

• Before-and-after method. Compares the business's performance before the wrongful conduct to after, attributing the decline to the defendant. It works best for an established business with a clean operating history.
• Yardstick method. Compares the injured business to a benchmark — a comparable company, a sister location, or industry averages — to estimate what it would have earned but for the wrong. It is often used when the business lacks a long internal track record.

Both must isolate the loss caused by the defendant from losses caused by the market or the plaintiff's own decisions — a frequent battleground on causation.

Business valuation approaches

• Income approach (including discounted cash flow). Projects future earnings or cash flows and discounts them to present value. DCF is powerful but assumption-heavy — small changes in growth or discount rate swing the result, making it a cross-examination magnet.
• Market approach. Values the business by reference to comparable sales or market multiples.
• Asset/cost approach. Values the business on the net value of its assets, used more for asset-heavy or holding companies.

A well-prepared appraiser typically considers more than one approach and explains the choice.

How experts are disclosed and deposed

Expert testimony is regulated by procedure, and missing a step can cost a party its expert.

• Disclosure. Under the Missouri Rules of Civil Procedure, parties must disclose their retained experts during discovery — identifying the expert and the subject matter, facts, and opinions to which the expert will testify, plus the grounds and data relied on. A late or incomplete disclosure can lead the court to strike the expert.
• Deposition. The other side may depose the expert under oath before trial, probing qualifications, assumptions, data, and method. This is where a damages opinion is stress-tested and where admissions that fuel a later motion to exclude are often obtained.

Because disclosed opinions and deposition testimony tend to lock in trial testimony, careful preparation matters.

Daubert challenges: motions to exclude

The flip side of the gatekeeping standard is the motion to exclude (often called a Daubert motion or a motion in limine), which asks the judge to bar the opposing expert's opinion before trial because it fails RSMo § 490.065. Common grounds include:

• Speculation. The opinion rests on conjecture rather than reasonable certainty — projections with no grounding in the company's records or comparable data.
• Unreliable methodology. The expert used an unrecognized or improperly applied method, cherry-picked data, or made unsupported assumptions.
• Lack of qualifications. The expert lacks the training or experience for the specific opinion offered.
• No fit / failure on causation. The opinion does not match the facts, or fails to separate losses caused by the defendant from unrelated factors.

A successful motion can gut a damages case, because excluding the only expert may leave a party with no admissible proof of loss. Even a partial win — narrowing what the expert may say — can sharply reduce the number the jury hears. This is why both retaining a defensible expert and challenging the opponent's are central to strategy.

Frequently Asked Questions