Reading Room

Every business subject to environmental law and enforcement needs expert witnesses at hearings, administrative or judicial proceedings. A witness qualified as an expert may testify within his sphere of expertise to matters of opinion, based on facts brought to the witness' attention by hearsay or hypothetical questions.

Every business subject to environmental law and enforcement needs expert witnesses at hearings, administrative or judicial proceedings. A witness qualified as an expert may testify within his sphere of expertise to matters of opinion, based on facts brought to the witness' attention by hearsay or hypothetical questions.

Many experts unfamiliar with judicial or administrative proceedings have the impression that scientific certainty is required when testimony is presented. In a scientific endeavor, it is not uncommon for experts to hesitate offering opinions without something resembling absolute certainty. However, in a courtroom this impression is incorrect.

In a criminal court, innocence is determined by proving there is "a reasonable doubt" to warrant a guilty verdict. In a civil court, if a case calls for an injunction or monetary damages, the standard of proof for liability is "more likely than not." In an agency trial, where a permit or enforcement order may be under review, the standard of proof to support the agency decision is whether there is "substantial evidence in the record." In other words, in most legal proceedings the decision maker is deciding which party is "more right", not whether perfect "truth" has been presented.


Preparation of testimony takes place before the hearing begins and throughout the proceedings. The expert witness should keep his perspective. He should remember that the entire case does not hang on one piece of testimony. The expert's reputation is not on the line and devastating cross-examination is rare. Perry Mason does not pierce through a case with a final, crushing question put to the opposing witness.

The expert's preparation involves review of all relevant deposition transcripts, technical reports, test results and previous case testimony. Testimony should be outlined but not drafted verbatim. The expert should rehearse testimony with counsel at least once. Time for practice sessions with other experts in the case should be allowed. He also must be knowledgeable about the matters in dispute, the facts presented as evidence.

An expert witness will not be able to read testimony from notes or reports for the court record. An expert is expected to be able to speak "off the cuff." This shows that the witness is truly familiar with the case. If the witness plans to bring notes to the witness chair, they must be effective, carefully prepared and organized.

A loose-leaf binder is a good approach for written material, with dividers for each major section of work performed or conclusions reached. Each section should contain the ultimate findings or opinions, followed by supporting documents and references. This organization pays handsomely in confidence, ready references and impact on the opposing counsel. The expert should be aware that the judge or hearing officer as well as opposing counsel is allowed to examine whatever is brought to the stand to testify. Consequently, the expert should be very careful about written materials.


Many people think cross-examination is the biggest challenge for an expert, but direct testimony, done properly, can be more of a struggle. Direct examination builds the case. Because direct examination questions must not be leading, the expert must know what counsel expects when asking general questions. The expert must take these questions as the cue to tell the story of his expertise, scope of work, findings of fact and opinions and conclusions.

If the expert has prepared a final report, this should be introduced as evidence and could be part of the presentation. The expert witness and attorney should prepare several new hypotheticals or other lines of inquiry to ensure that facts, opinions and conclusions are presented in logical procession so the judge, jury or hearing officer understands the scientific material presented.

The goal during direct testimony is to stress the expert's opinions and conclusions. The expert should avoid the usual mistake of dwelling on the scientific homework done leading those opinions and conclusions.

The expert will want to spice testimony with examples, maps and plans, photographs and diagrams, models and demonstrations if it helps express the message more clearly.


The opposing attorney is entitled to try to put words in the expert's mouth. These are called leading questions.

The witness' attorney will have a chance to redirect.

During cross-examination or re-cross, the expert should expect subtle and not-so-subtle attacks on work, findings, conclusions, credentials and credibility. The expert should rehears with counsel to identify the questions opposing counsel likely will ask during cross and develop effective answers. The expert should expect "trick" questions and be ready to extract from his experience things that support his credentials. The expert should be able to distill the field of expertise to a summary or title and to organize the exhibits relied upon for quick reference. Any reports should be mastered so important points, citations and supporting data can be cited easily.

The key to litigation is witness credibility. Opposing counsel will focus on the role the expert played in the matter, the specific basis for the professional evaluation, the complete set of tests and results relied upon and the key factors in the opinion. Using questions interrogatory in nature (simple questions), accusatory (framing the answers) or anticipatory (asking the expert to assume factors most favorable), the opposing attorney may:

  • Establish limitations on expert testimony because of inadequate budget or time for research or observation essential to framing an opinion;
  • Show limitations on the expertise;
  • Criticize the expert's misinterpretation or unfamiliarity with important technical or legal terms;
  • Illustrate that the expert disregarded or was unaware of important facts that would alter opinions or findings, or that the expert made favorable or erroneous factual assumptions;
  • Probe how the expert would modify opinions when key facts or assumptions are changed, using the questioner's assumptions to show how or whether the expert would change opinions dramatically; and
  • Attack the expert's credibility by showing that in similar cases the expert made inconsistent statements or inconsistent assumptions.

The cross-examining attorney will insist on responsive answers; restrict the witness to facts and opinions and not values; ask the witness to mark or indicate key items in the documents or on maps favorable to the questioner's case; define concepts in terms of the questioner; get the witness to admit he does not know; insist that the witness stay within the field of expertise for which he was qualified; have the witness admit the strong points of the opposing case; and steer the testimony by aid of leading questions.

Environmental professionals who are expert witnesses are a necessity for every business that wants to be successful. Their roles change to reflect the types of trial proceedings or hearings triggered by environmental permits, reviews or enforcement. The sophisticated business will understand and appreciate how best to utilize these experts and will select those who are best at advocacy in these forums.

Across the spectrum of environmental law we offer advice and representation
with practical, results-oriented lawyering.


Contact Information