The Wall Street Journal reported last week that a Chicago judge has barred the testimony of an expert witness in a lawsuit over firefighters' hearing loss. The judge ruled that Dr. William W. Clark couldn't testify after he learned that the defendant, Federal Signal Corp., had collected the data for a hearing loss study that Clark authored. How do you become an expert witness?
First, figure out your area of expertise. According to the Federal Rules of Evidence, an expert witness can be anyone with special "knowledge, skill, experience, training, or education." An expert can testify under the following conditions: The testimony must be based on sufficient facts or data; the testimony must be the product of reliable principles and methods; and the witness must have applied the principles and methods reliably to the facts of the case. In general, expert witnesses are called in when "scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue." And unlike ordinary witnesses, who can only testify on what they have seen or heard, expert witnesses can offer the court an opinion or conclusion.
Where do expert witnesses come from? A court may appoint an expert, and the plaintiff or defendant may select his or her own as well. In order to testify, expert witnesses must first be approved by the judge overseeing the case. An expert cannot be forced to testify in a case and is typically compensated for his or her work, though just how much varies from case to case.
How do lawyers find expert witnesses? Most often, they turn to literature—they will find out who wrote, say, a journal article that pertains to the case and contact the author. Lawyers often turn to universities in search of academics at the top of their field. As a last resort, a lawyer can turn to expert databases or companies that match experts with cases.
The use of expert witnesses has long been a source of controversy. In 1871, wealthy Baltimore widow Elizabeth Wharton was accused of poisoning her financial adviser and attempting to poison an accounting clerk in his office. The doctors who performed an autopsy on the financial adviser ruled that there had been foul play, but Wharton hired a "dream team" of forensic toxicologists to dispute the findings and the competence of the prosecution's experts. After she was exonerated, newspapers had a heyday with the case, arguing for the use of "official and impartial scientific expert witnesses."
These debates continue today, particularly over the use of scientific evidence. A 1993 Supreme Court decision, Daubert v. Merrell Dow Pharmaceuticals, radically changed the criteria for the admission of expert testimony. For 70 years, federal and state court judges had followed the dictates of the Frye ruling of 1923, which stated that the methods used by the expert must have gained "general acceptance" within the scientific community. Daubert transferred the authority to credit an expert from scientists to individual judges, making them the "gatekeepers" of scientific evidence in the courtroom. Under Daubert, judges are required to examine the underlying scientific method that experts employ and to admit only evidence that is "relevant and reliable." Critics of the Frye standard had argued that it kept new, legitimate science out of the courtroom. But since the Daubert ruling, the percentage of expert scientific testimony that's been excluded from courtrooms has increased.
Explainer thanks Jeffrey Kroll, co-chair of the Expert Witness Committee at the American Bar Association Section of Litigation, and Celeste Monforton, a research associate at George Washington University's School of Public Health and Health Services.
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