There are two broad categories of trial witnesses: the "lay" witness that is only allowed to describe her or his direct sensory information (heard, saw, etc.) and the "expert" witness who is allowed to express opinions and frequently was not present at the events that are the focus of the trial. This comment provides a brief and incomplete educational commentary concerning the expert witness. Always consult an experienced attorney in all specific situations.
Our judicial system is of two minds when it comes to juries. On the one hand, direct community involvement in the administration of justice is praised and on the other hand there is a fear that jurors will be swayed by emotion, bias, or other extraneous factors. The entire complex rules of evidence boil down to what information may or may not be presented to a jury and in what manner. Indeed, "juror misconduct" often involves improper sourcing of information, such as the Internet, or the improper sharing of personal experiences by and among jurors.
While we take for granted the concept of a "neutral" jury that knows nothing in advance about a situation, this is a development in English law from the 1600s in response to the use of trials for improper political purposes. Historically juries were more like modern witnesses and had independent powers of investigation. The modern grand jury (recognized in the Magna Carta in 1215) and the sometimes utilized coroner's jury (investigating deaths - inquests) have some of this historic broad power in contrast to the petit (trial) jury. One of the challenges of our information age is to adapt the administration of justice to current realities. My opinion is that trial procedures must allow juries great participation privileges, such as asking questions or being allowed access to some forms of non-testimonial information. Of course, this issue must be carefully considered prior to making significant changes.
Regarding expert opinion testimony, the fear has long been that juries will be over-swayed by "neutral" "credentialed" individuals who present "junk" science or "pseudo-science." Three 1990s U.S. Supreme Court decisions articulated standards for the admission at trial of expert testimony: Daubert v. Merrell Dow Pharmaceuticals (1993), General Electric Co. v. Joiner (1997), and Kumho Tire Co. v. Carmichael (1999). Collectively they created what is now called the "Daubert standard" for pretrial hearings before a judge who determines if a challenged expert's testimony may be heard by the jury. Federal Rule of Evidence 702 discusses expert testimony.
In summary overview, the trial judge has a "gatekeeper" function to determine that the proposed testimony is both relevant to trial issues and rests upon a reliable foundation. Reliable scientific knowledge, conclusions and opinions are equated with accepted scientific methodology. While these rules applied to federal courts, most but not all states also follow these standards. A trial expert must determine the procedural rules in a given jurisdiction.
Not every situation requires expert testimony and a litigant may challenge the introduction of expert testimony. What is within the common knowledge of the typical juror? Are there complex factual and opinion matters that an ordinary jury cannot readily analyze or form an opinion concerning? Is there too great an analytical gap between the available data and the purported conclusions that the expert will make? Perhaps the proposed expert is retired and not up to date on the latest understandings, or the proposed testimony is speculative or subjective guessing. In causation situations, where multiple causes are possible, the expert must be able to point to specifically known situational facts that support her or his theory of causation.
The use of social science expertise in legal argument dates from 1908 when Louis Brandeis (1856-1941) devoted most of his Supreme Court brief in Muller v. Oregon to expert analysis of the adverse impact that long working hours had on women. Of course, the famous Brown v. Board of Education (1954) Supreme Court decision discussed how segregated education was inherently unequal. The so-called "Brandeis Brief" is both praised and criticized.
Note, in this regard, that there are so-called "hard sciences" and so-called "soft sciences." Family law cases frequently involve child matters and financial matters. A determination of the present and future "best interest of the child" is not a matter of mathematical precision. While psychology and family therapy are legitimate disciplines, the question may become whether or not the proposed witness possesses a legitimate area of expertise and relies upon an established methodology within that discipline. The American Psychological Association (APA) has created guidelines for child custody evaluations. Has the proposed expert adhered to them? Has informed consent been obtained? Does the expert have conflicts of interest and multiple overlapping relationships with the various parties associated with the family law case?
Experts may come from an academic, industrial, or consulting firm background. Obviously one must conduct a thorough background investigation before engaging a particular expert. What a litigant doesn't know about a proposed expert or other witness may hurt. Consider the devastating cross-examination of a police detective in the famous O.J. Simpson murder trial. What is present in social media, blogs, and other researchable but "non-professional" content? Track the expert's career carefully with special attention to why career moves occurred. Did the expert move "under a cloud?"
One must be careful in pretrial communications. In fact, openly calling someone an "expert" has traditionally allowed opposing counsel to obtain all communications made with the "expert," attorney-client privilege and attorney work-product rules notwithstanding. Additionally, communications that the expert has with non-attorney individuals are not protected from discovery under privilege rules. This is a complex procedural topic and is additionally complicated by the fact that some witnesses, such as an attending physician, may be testifying both as a lay and expert witness. Federal Rule of Civil Procedure 26 generally addresses the duty to disclose and discovery.
Assuming that an expert will testify, the typical process is to initially question the witness in the presence of the jury concerning her or his knowledge, skill, training, education, and experience. Education or formal credentials are not necessarily required to make one a subject matter expert. Then the attorney asks the trial judge for permission to question the witness as an expert. Sometimes, as means to prevent this reinforcement of the witness's credibility, the opposing attorney will stipulate that the witness is an expert. However, if one plans to challenge the witness's expertise on appeal, one should not stipulate.
Successful trial practice is both an art and science. What should be presented to the jury and how should it be presented? Like Goldilocks' porridge, it should be not too little and not too much. Are visual aids possible? Is the expert an effective communicator and adapt at simplifying complex topic? Multiple experts on the same topic may end up contradicting one another. Perhaps a jury will best relate to an expert from a local college rather than a big-city university. Think like the jury. One cannot be over-prepared.
The credibility of any witness may be challenged at trial. An expert must be prepared to respond to challenges based upon credentials, fees, methodologies, and prior positions, among other things. Challenges during cross-examination might be based upon such things as a witness's prior inconsistent statements, the presence of prior criminal convictions or related character issues, showing bias for or against a party or having a monetary interest in the case (the traditional "hired gun" argument), attacking a witness's cognitive abilities, or contradicting the witness with a counter-witness. Is the witness able to stay polite, cool, and collected when attacked? Will the cross-examiner come across as exposing a fraud, or as a bully engaged in trickery? All of this requires a sensitive understanding of how this particular jury is likely to perceive these methods.
A "trial" is a testing. In the judicial context, the initial testing is to determine the facts - what happened and why did it happen? This may be more difficult than one may suppose. Pilate, speaking as a judge, is quoted in the Bible in John 18:38 as asking "What is truth?" Assuming this is a serious philosophical question, a seasoned courtroom observer may despair at what juries believe or fail to believe. In any event, the expert witness is part of the search for truth that occurs in the courtroom.
This comment provides a brief educational commentary and overview of a complex topic and is not intended to provide legal advice. Always consult an experienced attorney in all specific legal situations.