Judicial Notebook

Some of the most promising research in psychology and law has focused on issues of memory and cognition. Because eyewitness testimony is often valued by juries and the justice system alike, conclusions that eyewitness testimony can be inaccurate and overvalued are hotly contested by scholars and policy-makers. As additional studies build on older ones demonstrating that a host of memory and cognitive processes often involved in litigation can be unreliable-such as eyewitness identification-expert testimony related to these concepts has increased. The impetus of such testimony is heightened by the exoneration of many defendants by DNA evidence in cases where guilt was assumed to be "airtight." Testimony related to the limits of memory and how people cognitively process and recall information, however, have met timid waters in the courts. Recently, the District Court for the District of Columbia disallowed expert testimony on memory in the highly publicized case of Libby v. U.S., 05-394 (2006). The holding of the court suggests a deep skepticism of the proffered testimony and eschews its use because of a number of methodological shortcomings in the research studies themselves.

The Libby case

I. Lewis "Scooter" Libby Jr. was indicted in 2005 on numerous charges related to the alleged disclosure of covert CIA agent Valerie Plame. In what has become commonplace in federal prosecutions, the thrust of the government's position rests on the allegation that Libby committed perjury by lying to FBI agents and a grand jury regarding his recollection of a conversation he had with members of the press several years ago. Specifically, Libby argued that the alleged false statements were not intentionally false, and instead the result of faulty memory and confusion. To assert this defense, Libby hired several renowned psychologists who were prepared to testify that research has demonstrated that lay jurors often underestimate the frequency of errors present in memory testimony and recall of past events is subject to distortion.

The government countered, claiming that such expert testimony was inappropriate under the Federal Rules of Evidence and extent federal case law. During the government's motion in limine, defense experts were vigorously challenged regarding the validity and appropriateness of their proposed testimony. On Nov. 2, 2006, Judge Reggie B. Walton issued a 27-page ruling excluding the expert testimony based on the Federal Rules of Evidence Section 702 and the watershed case, Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579 (1993).

Daubert and expert testimony

In order for expert testimony to be admitted in federal court, the proponent must demonstrate by a preponderance of the evidence that such testimony is based on scientific studies that are methodologically valid and that such testimony has a reasonable application to the facts at hand during trial. As mentioned by the court, the Daubert case and the pertinent Federal Rules of Evidence 702 is considered by most legal scholars as a liberalization of expert testimony guidelines in favor of allowing such testimony. Indeed, the court cites numerous appellate cases holding that uncertainty regarding expert testimony should favor admission. Nonetheless, the court barred the proposed testimony on four grounds: such testimony would not assist the jury; the testimony would usurp the role of the jury in deciding issue of credibility; the prejudicial effect of the testimony outweighed its probative value; and the validity of the underlying studies were in question. Of the four, the court weighed heavily on the last in its opinion.

Finding that most of the cited cases in memory research were conducted in university settings without the aid of vigorous cross-examination, voir-dire, closing arguments and jury instructions, the court held that such studies failed to demonstrate how jurors evaluated claims of memory impairment during an actual trial. Stating that many of the underlying studies were of "suspect" quality, the court directly questioned whether existing research based mainly on eyewitness testimony was applicable to more general questions of memory and recall. Finding fault with both the analytical reasoning of the proposed testimony and the studies themselves, the court held that allowing expert testimony constituted an undue delay and "waste of time."

Law meets science

The Libby case is a good demonstration of how law and science approach problems from fundamentally different perspectives. As Judge Walton's opinion makes clear, there is a strong penchant toward preserving the structure of the legal proceedings. Juries, not experts, are favored in deciding issues that smack of credibility. Irrespective of what science has demonstrated about memory and cognition, expert opinion about such facets of cognition-however methodologically sound or flawed-are inherently distrusted because they inject science into a normative process that jealously guards traditional notions of juror discernment and judgment.


Judicial Notebook is a project of APA's Div. 9 (Society for the Psychological Study of Social Issues).