Who is an expert? A quick primer on an evasive concept.

175 T o many physicians, the term expert witness not only raises the specter of a “hired gun” willing to testify against his colleagues for financial gain, but often leads to exasperation when learning that the expert is not even in the same field of medicine as the person he is testifying against. Similarly, many physicians express reluctance to act as an expert in legal proceedings because they do not consider themselves to be an expert in their field. The effort here is to clarify what the term expert means in legal proceedings and how courts determine whether that label is merited. Each jurisdiction has procedural rules that outline what is generally required to be considered as an expert witness (1). Two circumstances must exist before an individual can testify as an expert witness in a legal proceeding. First, the court must find that there is an issue before it in which expert testimony is needed to guide the jury. Otherwise, the opinion of the expert is not relevant. Second, the court must find that the individual tendered as an expert has sufficient qualifications. In Texas, the rules provide that expert testimony is relevant and allowable “if scientific, technical, or other specialized knowledge will assist the [jury] to understand the evidence or determine a fact issue” (2). More simply put, there must be an issue before the jury that is outside the lay public’s general knowledge and experience (3). The applicable standard of care and whether or not improper care caused injury (“causation”) in health care liability claims are two such instances in which it is well recognized that expert testimony is relevant (4). In fact, because the common experience of lay persons is not sufficient to allow a jury to determine liability and causation in health care liability claims, expert testimony on those issues is required (5). Since expert testimony in health care liability claims is almost always relevant, the focus in health care liability claims is on the second issue, the qualifications of the witness tendered as an expert. In vetting an expert’s qualifications, the role of the trial court is to ensure that “those who purport to be experts truly have expertise concerning the actual subject about which they are offering an opinion” (6). The burden is on the party offering the witness as an expert to establish that the individual has the proper credentials to qualify as an expert (6). In general, courts base this determination on review of the witness’s “knowledge, skill, experience, training or education” (1). In Texas, when expert testimony pertains to whether a physician departed from the applicable standard of care, the party tendering the expert must also establish that the witness meets four criteria: • Is a physician • Is practicing medicine at the time of the testimony or was practicing at the time the claim arose • Has knowledge of accepted standards of care applicable to the diagnosis, care, or treatment of the condition or illness at issue • Is qualified to offer an opinion on the applicable standard of care based on training or experience (7) Court judges receive a great deal of discretion in determining whether or not an individual qualifies as an expert witness. When these decisions are reviewed by appellate courts, the focus is not on whether the appellate court considers the trial judge’s decision correct but on whether or not the trial judge followed the applicable guiding principles in reaching his decision (8). Given this standard of review, it is not surprising that a great deal of judge-to-judge and even case-by-case variation exists. While resolution of a particular situation is highly dependent on the individual judge addressing the situation, a few cases are illustrative of what is needed to pass muster. While physicians do have specialized knowledge beyond that of the lay public based on their knowledge, skill, experience, training, and education, that general specialized knowledge alone is not necessarily adequate to qualify a physician as an expert witness (9). The witness must be shown to have “special knowledge as to the very matter on which he proposes to give an opinion” (6). To meet this burden, the evidence should show how the witness has particular expertise in a relevant area, not simply that the witness has more expertise than the man on the street. The ultimate goal is to provide the court with sufficient information to ensure “that those who purport to be experts truly have expertise concerning the actual subject matter about which they are offering an opinion” (6). However, it is not required that the witness be from the same specialty