Choice of Language and the Communication of Expert Opinions and Testimony
5.1 Experts and attorneys should attempt to understand the differences between their own professional concepts and legal definitions and standards to avoid confusion in opinions.
Experts and attorneys often differ in the terms of art they use in their respective professions. For example, physicians and attorneys differ in their defining of causation. This often leads to misunderstanding when the physician is asked an expert opinion on the issue of legal causation.
Medical etiology is the science of determining the causes of disease requiring medical treatment. As such, it is concerned with all possible causes. Through differential diagnosis, these causes can be narrowed such that treatment is rendered based on a final diagnosis. Therefore, the physician focuses primarily on those causes which are still operative and can be controlled, altered, or removed by treatment such that the outcome is affected. Legal causation focuses on these earlier precipitating or aggravating causes brought about by allegedly tortious conduct. Legal causation is a political and social decision as to where society feels a loss should fall. It is a factual determination, based on legal standards, as to whether a sufficient causal relationship exists between the alleged wrongdoing and the injury complained of.
Legal causation therefore has little to do with medical etiology and focuses on the role of a single past traumatic event rather than all possible causes and conditions contributing to a medical condition.
A legal cause is often defined as a cause without which the claimed injury would not have occurred. A legal cause is also sometimes defined as conduct which is a "substantial factor" in bringing about the claimed injuries. It need not be the sole cause nor the last or nearest cause.
So long as it is a cause, it does not matter that it joined with other causes to bring about the claimed injury.
In cases where an underlying symptomatic medical condition was aggravated or worsened by a defendant's conduct, the defendant will only be responsible for that portion of the total harm caused by his or her conduct. These cases often require a physician's opinion attempting to apportion the plaintiff's underlying condition and the aggravation of that condition by defendant's conduct. If apportionment is impossible, the law will hold the defendant legally responsible for all of the harm. However, under the law there should be no apportionment made for asymptomatic pre-existing physical frailties, mental conditions, illness, etc. that may have made the plaintiff more susceptible to injury, disability or impairment.
Accountants, engineers, and court reporters may all use terms and concepts which differ from the meaning which attaches to those terms and concepts in a legal setting. Thus, experts and attorneys need to be clear on the other professional's use of various terms and concepts that may differ from their own.
5.2 An expert should understand the legal standards of proof and evidentiary rules concerning expert opinions, and attempt to express opinions by using necessary legal terminology.
Each profession has a highly technical language largely unknown to the other. This technical terminology is needed in each profession to attain accuracy and certainty of meaning. However, while this terminology facilitates understanding within a profession, it often blocks understanding between professions. Experts reporting or testifying in a lawsuit or claim should attempt to understand some of the legal standards of proof and technical terminology. The expert should understand that law is largely a profession based on words and language. Therefore, while many legal terms are foreign to the expert, they are of critical importance in stating a relevant and competent legal opinion.
Foremost among these necessary legal terms is "reasonable probability." To be competent, an expert's opinion should generally be based upon "reasonable probability." This term simply means that which is more probable than not, more likely than not, or over 50 percent probable.
This is consistent with the legal standard of proof that findings must be based upon probabilities and not possibilities. Opinions based upon surmise, speculation, or conjecture are irrelevant and inadmissible in law. However, an opinion need not be based upon scientific or medical certainty, which is a far more stringent standard than the law requires.
Therefore, experts should attempt to express their opinions using such terms as "reasonable medical probability," or "probably" or "likely." Terms such as "possible," "might," "may," "could," "guess," "maybe," and the like may, under some circumstances, render the opinion inadmissible.
Similarly, before testifying regarding a medical or professional liability claim, the expert should be thoroughly versed on such terms and issues as "standards of care," "negligence," "respectable minority," "judgment calls," etc.
It is the responsibility of the attorney requesting an expert opinion to educate the expert concerning the legal standards of proof and the significance of technical legal terminology. This can and should be done in the various meetings with the expert and any letters requesting a formal opinion.
5.3 Experts should use clear, plain and understandable language when testifying and should attempt to avoid overuse of complex terminology.
An expert may have an excellent command of the facts and the professional language of his or her specialty and may be adequately versed in the legal terminology. However, the expert must communicate his or her facts and opinions consistent with the level of sophistication of the fact-finding body hearing the case. Expert testimony may be so technically worded that its meaning is entirely lost to the jury or is so completely misunderstood that the jury arrives at a verdict that would have been different had it known the true import of the testimony.
The expert witness should remember that his or her role is essentially that of a teacher. The testimony is not intended to impress or edify, but to explain. If the testimony does not help explain and does not clarify the issues of a particular case, it has failed in the sense that it was not useful to the determination of the case.
To make expert testimony clear, an expert witness should preferably express his or her findings and opinion in medical or technical terms first. Those terms should then be translated as accurately as possible into language intelligible to the court, attorneys, and jury.
The attorney should assist the expert witness in choosing appropriate terminology and then monitor the testimony. If undue use of complex terminology is made by the expert, it is appropriate and even recommended that the attorney interrupt the testimony and obtain necessary clarification.
In complex cases, it may be appropriate to compile a glossary of terms and definitions which, with permission of opposing counsel and the court, may be provided to the jury.