Medical examiners often serve as expert witnesses in criminal trials, grand jury hearings, coroner’s inquests, and other legal proceedings. Many testify on behalf of the governmental body that employs them, but pathologists and retired medical examiners are also asked to serve as expert witnesses for private parties.

Any case in which cause of death, time of death, or the circumstances surrounding death must be established can give rise to the need for expert testimony. Two recent news stories about medical examiners shed light on how juries assess their credibility.

Qualities that make a medical examiner’s testimony credible

Dr. Donald Reay retired as the medical examiner in King County, Washington in 1999. His exemplary performance in the job was recently recognized by the National Association of Medical Examiners. The organization is honoring Dr. Reay with the Milton Helpern Laureate Award, “the nation’s most prestigious award for medical examiners.”

According to King County Superior Court Judge William Downing, Dr. Reay “embodied all of the attributes of the ideal expert witness.” Judge Downing identified those qualities as intellectual curiosity, scientific objectivity, and unshakable honesty. Dr. Reay was also praised for his vast knowledge and for his ability to communicate that knowledge by speaking to juries as a “regular guy.”

Unlike expert witnesses who “become advocates and lose their credibility,” Judge Downing said that juries trusted Dr. Reay because he never lost his objectivity. That opinion is consistent with Dr. Reay’s view of his role as an expert. Instead of viewing himself a witness for the prosecution or the defense, he testified as “a witness for the dead.”

Qualities that make a medical examiner’s testimony doubtful

Radley Balko has written a number of columns for The Washington Post that are critical of Mississippi medical examiner Steven Hayne. As an expert witness employed by the state, Hayne became controversial due to his perceived willingness to slant his testimony to favor the prosecution.

A number of convictions based on Hayne’s testimony have been overturned on appeal — including one that nearly resulted in an execution — based on doubts about the validity of Hayne’s expert testimony. Court decisions make clear that Hayne, unlike Dr. Reay, adopted the role of an advocate rather than an expert whose opinions were based solely on an objective analysis of the facts.

The Mississippi Department of Public Safety became so frustrated with Hayne (who at one point performed a remarkable 1,800 autopsies a year) that it took action to prevent him from doing autopsies. That action effectively barred him from testifying as an expert for the State of Mississippi, despite efforts of the state’s Attorney General to keep him employed.

As Randy Balko reports, once Hayne could no longer testify for the prosecution, he became a defense expert. His controversial past, however, has affected his credibility in that role.

In a recent case, Hayne contradicted the prosecution’s medical experts, who testified that an alleged murder victim died from a blow to the head. Hayne testified that the alleged victim died from a drug overdose after combining anti-depressants with alcohol.

During cross-examination, the prosecutor pointed out that a number of convictions had been reversed based on Hayne’s improper testimony. Hayne’s willingness to testify outside the area of his expertise provided additional fodder for the prosecutor on cross-examination.

Of course, there is no little irony in the spectacle of prosecutors attacking the expert they once relied upon to help them secure murder convictions. As Balko remarks, the State of Mississippi is “arguing that Hayne both is and isn’t qualified and credible to testify as an expert witness — depending on whether he’s testifying for or against the prosecution.”

Medical examiners who testify as expert witnesses should follow the path of Donald Reay, not that of Steven Hayne. A credible medical examiner is one who is an advocate for the truth, not an advocate for the party who is paying for the expert testimony.