I. Introduction
Expert witnesses are pivotal in construction disputes, often serving as the linchpin for one side’s narrative. Credentials, such as a PE license or architectural degree, impress the bench, jury, or arbitrators and may be essential to prove a deviation from the “standard of care.” Frankly, if someone can pay the right price for a credentialed expert, they are likely going to find one willing to offer an opinion critical of your client. That is why in most jurisdictions and venues, cross-examination that targets methodology rather than qualifications often yields the most compelling cracks in witness credibility.
One way to challenge an expert’s reliability is to test their adherence to recognized standards, such as ASCE’s ethical mandates and ASTM’s forensic protocols, that mirror the “scientific method.” By using those standards tactically, you can expose bias, incomplete analysis, or trial-outcome-driven opinions, while also ensuring your own expertise is beyond reproach.
II. Credentials vs. Methodology
Missouri courts, as an example, have allowed experts to opine outside their specific credentialing when there is specific subject-matter overlap. Still, credentials alone are rarely discredited unless the witness’s methodology falters. The pivotal and often vulnerable arena is testing how the expert arrived at their opinions. I am a strong believer in the principle that, in deposition, is precisely where you want to ask “why” and “how” questions. Did the expert follow due diligence? How? Did they adhere to structured, objective protocols or succumb to advocacy-driven shortcuts? How? If not, why not? That’s where cross-examination can hit home.
III. Recognized Standards for Expert Diligence
- ASCE’s Ethical Framework for Engineers
The American Society of Civil Engineers (ASCE), a membership organization that has published a “Code of Ethics,” enshrines several foundational principles and canons crucial to expert credibility. Fundamental Principles include being honest and impartial (Principle 2), serving with fidelity to public interest (Principle 2), and striving to enhance the integrity of the profession (Principle 3).
- ASTM Standards for Forensic Expertise
The American Society for Testing and Materials (ASTM) formed its Committee E58 in 2008 to promote Forensic Engineering knowledge and the development of appropriate standards intended to promote the awareness of the scientific, engineering, ethical, and legal considerations inherent in Forensic Engineering investigations, reporting, and testimony. It has since adopted standards including guidelines, definitions, methods for the collections, preservation, scientific examination, and description of physical evidence for purposes of dispute resolution, or reporting to a court, and the general practice of Forensic Engineering.
Those guidelines include:
- ASTM E2713-25, “Standard Guide to Forensic Engineering,” emphasizes qualifications, ethical practice, and standardized methods for investigative rigor.
- ASTM E3176-24, “Standard Guide for Forensic Engineering Expert Reports,” the updated guide for forensic-engineering expert reports, provides disciplined guidance for writing reports, highlighting scope, content, limitations, authorship responsibilities, and representation in litigation.
ASTM E2713-25 frames what “good” looks like for a forensic-engineering expert without turning it into a rigid checklist. In plain terms, it expects the expert to be properly qualified in the specific branch of engineering at issue, to approach the assignment with the same rigor they would bring to design or analysis work, and to keep the role of impartial explainer front and center. That means planning the investigation, preserving and evaluating data, separating facts from assumptions, and applying accepted engineering methods that are transparent and reproducible. It also means acknowledging uncertainty and limitations so the reasoning path from data to opinions is visible and testable.
The guide couples that technical rigor with professional obligations: objectivity over advocacy, clear documentation of methods and findings, and reporting that accurately reflects what was done and why. While E2713 isn’t an evidentiary rule, it aligns neatly with admissibility expectations (think Daubert/Kumho) by emphasizing methodological reliability, relevance, and a defensible bridge from evidence to conclusions. For specialized tasks, testing, photography, reconstructions, and discipline-specific analyses, the standard points practitioners to the more detailed ASTM E-series references, reinforcing the idea that solid forensic work is both principled and appropriately tailored to the problem at hand.
ASTM E3176-24 is the reporting companion to the practice guide for forensic engineering: it tells experts how to build a clear, defensible written report. In short, it defines the report’s purpose and scope, lays out the core content (facts and data relied upon, methods used, analyses performed, opinions and their limitations), and reminds authors to separate observations from assumptions while making the reasoning path traceable from evidence to conclusions. It also addresses practicalities, how the report is represented in electronic form, and the expectation that one identifiable professional takes responsibility for the report as a whole (with joint authorship possible), recognizing that this person will likely be the initial focus of deposition or courtroom examination.
While E3176 isn’t an evidentiary rule, it’s written to align with admissibility expectations: methodological reliability, relevance, and transparent documentation. The guide explicitly notes its limits (it does not resolve safety or regulatory questions for you) and positions itself alongside other ASTM E-series standards. Use it to structure the report, then pair it with discipline-specific methods for the underlying work. The payoff is a report that reads cleanly, travels well in discovery (including digital formats), and stands up when the author is questioned on what was done, why it was done that way, and what uncertainties remain.
IV. Targeting Gaps in the Expert’s Methodology
Cross-examination should go beyond mere poking at credentials. Focus instead on whether the expert:
- Failed to follow ASTM-style methodology, for example, by not ruling out alternative causes systematically.
- Ignored relevant ethical obligations under ASCE, such as issuing statements without sufficient objectivity or competence.
- Relied solely on client-supplied data, without independent review or verification.
- Invoked “reasonable degree of scientific certainty” without adhering to rigorous hypothesis testing or alternative elimination.
V. Common Cross-Examination Angles Using Industry Standards
A. Failure to Rule Out Alternatives
Ask: “Did you consider [insert alternative cause]? What tests did you conduct to rule it out?” If the expert omitted such steps, you can cite the ASTM guidelines and pinpoint their deviation.
B. Departure from Recognized Protocols
For example: “Did your analysis include independent data collection, hypothesis testing, and elimination? Did you follow those steps?”
C. Over-reliance on Assumptions
Challenge: “Did you personally visit the site? Test the samples? Or did you rely only on documents from counsel?” Such questioning highlights a failure of due diligence.
D. Indicators of Bias
Probe language: “Your report concludes ‘to a reasonable degree of scientific certainty’ but without applying ASTM protocols or ruling out other causes, how can you have any level of certainty (it’s more advocacy than science)?” Then tie it back to ASCE Canon 3 about objective and truthful statements.
E. Misuse of “Scientific Certainty”
Push back: “The phrase ‘reasonable degree of scientific certainty’ implies exhaustive testing and elimination of reasonable alternatives. Did you conduct those steps according to ASTM?”
VI. Structuring the Cross-Examination
Preparation
- Study the ASTM and ASCE standards thoroughly.
- Cross-reference the expert’s report and deposition to the steps and tenets of those standards.
Document Use
Use ASTM and ASCE standards as learned treatises, introduce them via deposition or expert testimony to show the benchmark your opposing expert failed to meet.
VII. Caution: Vetting Your Own Expert
This approach cuts both ways. If you criticize adversary experts for ignoring ASTM protocols or ASCE ethics, your expert must not be vulnerable to the same critique. Ensure your expert:
- Has followed ASTM steps.
- Has documented alternative hypotheses and their elimination.
- Is within their zone of competence (ASCE Canon 2).
- Is objective, truthful, and respectful of public welfare (ASCE Canons 1 & 3).
VIII. Practical Example: Cross-Examination Script Snippet
Q1: “Mr. Expert, are you familiar with the ASTM forensic investigative process?”
A1: “Vaguely.”
Q2: “These guidelines require generating multiple hypotheses. Did you do that?”
A2: “No.”
Q3: “They require testing each hypothesis, via lab, modeling, or field testing. Did you test anything?”
A3: “No, I relied on information from counsel.”
Q4: “You didn’t rule out other plausible causes, correct?”
A4: “Correct.”
Q5: “And under ASCE Canon 3, you must issue objective, truthful statements. Is it truly being objective to declare causation without testing any other possible alternatives?”
A5: “No.”
Q6: “Do you consider your opinion complete?”
A6: (Invariably they will say…)“Yes.”
This script exposes methodological gaps and anchors them in explicit standards, and shows their bias, possibly creating further credibility problems.
IX. Conclusion
In construction litigation, expert testimony often stands or falls on methodology, not credentials. Armed with ASTM’s forensic-engineering standards and ASCE’s ethical canons, a skilled litigator can expose flaws in an opposing expert’s approach while safeguarding their own. By focusing on scientific inquiry, objectivity, and professional responsibility, you can shift the spotlight from elitist qualifications to the scientific rigor, and in so doing, weaponize methodology as your best cross-examination tool.