If Memory Serves

Our Constitution guarantees every person accused of a crime the right to call witnesses in his or her defense. This right is so critical to fundamental fairness that trials in which it is not safeguarded have been deemed by the U.S. Supreme Court to suffer from a "structural error" so serious that an automatic reversal of any criminal conviction is always required, no matter how heinous the crime.

The central theory of Mr. Libby's defense was that if he made any misstatements, either to the FBI or to the federal grand jury, they were caused by faulty memory -- either his or that of the witnesses who testified against him. For over 30 years, psychological scientists have studied the mechanics of memory and conducted extensive and rigorous research on the subject -- reaching conclusions that are generally accepted in the scientific community. Of signal importance to the jurors in the Libby trial, the science of memory is diametrically opposed to the popular understanding of how the memory and the mind work...

The Libby defense team planned to call Robert A. Bjork, a distinguished member of the faculty at UCLA and a person so qualified in his field that the special prosecutor, Patrick Fitzgerald, did not even contest the point. Moreover, the trial judge, Reggie Walton found the proposed evidence sufficiently reliable to satisfy the Supreme Court's stringent Daubert standard for the admissibility of expert-witness evidence.

However, after a day-long hearing (during which one of the authors of this article testified), Judge Walton barred Dr. Bjork from appearing as an expert witness. Essentially, the judge held that the science of memory is not "science" at all, but common knowledge and common sense. He further held that the right of cross-examination was an effective substitute for the right to offer evidence. Finally, he held that the proposed evidence was more likely to confuse the jury than educate it...

The Scooter Libby verdict was neither fair nor just because the jury never heard one of the most important pieces of evidence: an expert explanation of why faulty memory could be consistent with innocence.

Ms. Loftus is a professor of psychology and criminology at the University of California, Irvine. Mr. Steinberg is a criminal defense lawyer based in Detroit.