Working with experts
The challenge that happens before anyone hears the opinion
An opinion can be excluded for lack of a reliable basis. In a case where the whole dispute is expert evidence, exclusion is effectively decisive, which is why these motions are made.
The standards
Daubert, Frye and what applies where
Federal courts apply the standard from Daubert, under which the trial judge acts as gatekeeper and assesses whether the reasoning and method are reliable and fit the facts. Most states have adopted some version of it. A minority continue to apply the older Frye test, which asks whether the method is generally accepted in the relevant field.
The practical difference in condemnation is smaller than in scientific litigation, because the methods at issue, sales comparison, cost and income, are long established and not seriously contestable as methods. Challenges therefore tend to focus on application rather than methodology: not whether the sales comparison approach is reliable, but whether this expert applied it to data that supports the conclusion.
Which standard applies in your state matters, and so does the local practice on when these motions are heard. Both are questions for counsel at the outset rather than at the pretrial conference.
Grounds
What exclusion motions actually argue
| Ground | Typical form in condemnation |
|---|---|
| Qualification | The appraiser is opining on planning probability or engineering feasibility |
| Unreliable basis | Adjustments with no derivation; a capitalisation rate with no source |
| Unverified data | Comparable sales taken from records and never confirmed with a party |
| Project influence | Sales affected by the project used as evidence of value |
| Wrong legal standard | Valuation at the wrong date, or under the wrong definition of value |
| Ipse dixit | The conclusion rests on the expert’s say so rather than on anything shown |
| No fit | An opinion that does not answer the question the case presents |
Defence
What makes an opinion resistant
Standard method, applied conventionally
Novelty invites challenge and almost never helps in a field where the accepted approaches already work.
Derivations shown
Every adjustment traceable to data. This defeats the most common form of the motion.
Verified data
Sales confirmed with a party and the verification recorded in the file.
Scope discipline
The expert stays inside their qualification and relies on others for the rest.
Assumptions sourced
Each one identified, with its origin, so the expert is not defending an opinion they did not form.
The correct legal standard
Right valuation date, right definition, right treatment of the project.
Questions about admissibility
How often are condemnation experts excluded
Outright exclusion is uncommon. Partial exclusion, where an expert is barred from opining on a specific issue outside their field, is much more common and can be nearly as damaging.
Can an appraiser rely on another expert’s conclusion
Generally yes, where it is the kind of material experts in the field reasonably rely on. The reliance must be disclosed and the other expert should usually be available to testify.
What happens if an expert is excluded
In a case whose only dispute is valuation, the party is usually left without evidence on the central issue. It is as close to decisive as a procedural ruling gets.
When are these motions heard
Usually pretrial, often after depositions. That timing is another reason the deposition is where cases are won.
The expert decides the number more often than the argument does
In condemnation the facts in dispute are technical. Who presents them, and how well, is usually what the case turns on.