The USA Today cover story on June 21, 2006, adds to the chorus of controversy over the use of expert testimony, particularly mental health experts (psychologists, psychiatrists, therapists, etc), at trials. This article uses the Andrea Yates murder conviction (the woman who drowned her five children in the family bathtub), and the subsequent determination by the Texas Court of Appeals that her conviction should be overturned and a new trial should be conducted, as a springboard to analyze some of the risks associated with use of expert testimony at trial.
Expert testimony is explicitly recognized by Courts in the Rules of Evidence as providing important and beneficial assistance to juries. However, expert testimony involves the risk of so-called “junk science” wherein the expert, paid for his or her opinions, will offer whatever testimony the proponent “pays” to hear. The more definite the science, the easier it is to attack “junk science” expert testimony. For example, when calculations or known scientific formulas are involved, it is easier to “check the work” of the expert and expose flaws in that process than it is if the testimony is more theoretical or less susceptible to verification, such as psychiatry.
Over the years, the Supreme Court has advanced various methods to attempt to limit or regulate what kind of expert testimony will be allowed. Unfortunately, a categoric description of what is and is not proper testimony is often difficult to apply, and trial and appeals courts are often in conflict over this application. As the USA Today article points out, it is often difficult to determine whether the proffered expert testimony meets the general guidelines of admissibility or falls outside those parameters.
Adding to the confusion on this point are the variations that occur state to state. Use of expert testimony in Federal courts is currently governed by the so-called Daubert doctrine (names for a case), with varying interpretations. Some states have adopted similar [but often slightly different] state doctrines, while others have taken a more divergent view. As a result, the nature and extent of what expert testimony will be allowed in a given trial can vary widely from state to state, and even between the state and federal courts in the same state.
In recent memory, the O.J. Simpson criminal case brought public scrutiny on the use of experts in trials, with varying opinions on the topic. It appears that the Andrea Yates case, and others like it, will keep this debate alive for the foreseeable future. The Yates case, and the USA Today article, raise the issue of how religious beliefs may be used by the expert witness in determining sanity. This is likely to prove a flashpoint for public discussion..