June 04, 2007

Squash the experts before they can multiply

The January issue of the American Psychological Association's journal, Monitor on Psychology, has a column called "Judicial Notebook," which describes Judge Regie B. Walton's decision in the perjury trial of "Scooter" Libby to not allow the proposed expert witness testimony of psychologists specializing in memory and cognition. The judge offered four grounds for his decision: (1) such testimony would not assist the jury; (2) the testimony would usurp the role of the jury in deciding the issue of credibility; (3) the prejudicial effect of the testimony would outweigh its probative value; and (4) the validity of the underlying studies were (sic) in question. Linguists who testify as expert witnesses have heard these grounds before.

Judges have the right to make such judgment calls. That's one reason why they're called judges. But it's often not very clear why they rule the way they do. For example, why did the judge think that the testimony would not assist the jury in this case? I don't know what the experts said in their offers of proof but, based on my own experiences in such hearings, there can be lots of problems. Sometimes the offer of proof is written by attorneys who may or may not fully understand what the expert is going to say. And sometimes they don't make their case very effectively even when they do understand. In some cases the offer is made orally at a hearing, either by the lawyer or the expert. Again, from my own experience  in such hearings, judges may not hear the experts out, cutting them off when they are only part of the way through what they are trying to say, and never letting them get to the gist of their proposed testimony. When this happens, the experts may not have followed Grice's maxims very well and, therefore, they may have failed to convince the judge that their testimony would assist the jury. Many experts aren't familiar with the language of the courtroom or, for that matter, with the jargon-free language that might communicate to non-expert jurors. If the experts make their case well, however, they should be able to make a dent in Judge Walton's first objection: that such testimony would not assist the jurors. Whether judges agree to this, or even listen to it, is another matter, since they're the ones in the catbird seat.

Judge Walton's second objection, that such testimony would usurp the role of the jury, is another familiar judgment call. If the experts have had any experience in the role of an expert witness at trial, they will know, or will soon learn, where the boundaries are for this. The role of the jurors is to listen to the facts of the case and then to make an informed decision in their verdict. The facts of the Libby case came from the testimony of witnesses and the documents in evidence. Typically, experts can assist the jurors to do their job by providing them with the essential insights of their field that are relevant to the evidence. But they should never tell the jurors what to do with these insights about the evidence. That would be a judge's greatest fear. But getting beyond that fear can be difficult for judges because judges, being guardians at the gate, sometimes infer that it will happen anyway.

When experts have been careful to proffer their testimony in ways that put them in good shape to be admitted, a judge's ruling against them is sometimes based on an unfortunate inference. There are several reasons why judges infer that the expert will cross the line, even if nothing was said that would justify that they might do so. As noted above, one reason is that the expert's potential testimony may not have been made clearly and effectively. Another reason is that judges may fear that skillful attorneys might lead their experts out of their prescribed and proper roles. By then it would be too late and the damage couldn't  be undone. Experienced and competent experts know how to avoid this, but the judge has to make an early judgment call about whether it might happen. Other reasons are known only to the Court, but it is suspected that such things as the possibility of lengthening the trial come into play at least once in a while. The judge's fear about the potential of usurping the role of the jury is often based on the judge's fear of a potential courtoom calamity.

Things get even more complicated with Judge Walton's third ground for exclusion: the testimony's prejudicial effect on the jury that would outweigh its probative value. Byran Garner's Dictionary of Modern Legal Usage (Oxford 1995) defines "prejudicial" as "tending to injure; harmful." (WNCD's definition is equivalent) Garner adds that in the legal context, "prejudicial" applies to things and events, in contrast with "prejudiced," which applies to people. So Judge Walton was not saying that the psychology experts were prejudiced, but rather that allowing them to testify in this case would have a harmful or injurious effect. Again following Garner, "probative value" means "tending or serving to prove." So, translating the judge's objection number three leads to: "the harmful effect of the testimony would be greater than what it might prove."

I have no idea what Judge Walton was thinking about here. Perhaps he was right that the psychologists' testimony would have been harmful. But how? If they were indeed bona fide experts in their field of memory and cognition, and if what they had to say would stick to the issues of the evidence, and if this would help the jurors better understand what to do with the evidence when they deliberated, then it's hard to see how this could be harmful. If they were proper expert witnesses, they wouldn't even try to prove anything; they would enlighten the jury about aspects of memory and cognition that laypersons don't often know, things that would help the jurors decide whether the evidence put before them was proved.

On the surface at least, it looks like Judge Walton just didn't want to hear any more expert testimony. Unless he knows more about memory and cognition than the experts know, it would be hard to imagine how he could decide whether or not this would not assist the jury. His fear that the experts might wander off into territory of the ultimate issue of guilt or innocence is just that--a fear. But all this is moot if the experts' proffers gave clear signals that they were likely to go that route.

Judge Walton's fourth objection, the questionable validity of the studies underlying what the experts proposed to say, may or may not have been accurate. I suspect that the lawyers and witnesses must have gone around and around about this in a hearing, assuming that there was one.

The judge's  objection here was that the memory research cited was carried out in university research settings. He ruled that the psychologists did not approximate the legal context that contained a vigorous cross-examination, voir dire, closing arguments, and jury instructions. To him, these are very different things. He's right about that. But the larger question is how better can we find out important things about memory and cognition without studying them in contexts that are controlled? I'm sure that the psychologists understood that they were doing experimental, laboratory-style research. That's what they usually do and it's hard to imagine how an experimental research study on memory could take place in a courtoom context. The psychologists must have believed that their research has some useful relationship to the activities of the rest of the world, even to perjury cases like this one.  But nothing seems to be quite like the world of law.

Update: Mike Maltz writes to inform me that Judge Walton probably based his decision on the skewering that Prosecutor Patrick Fitzgerald delivered to memory expert Professor Elizabeth Loftus at a pretrial hearing.

Posted by Roger Shuy at June 4, 2007 05:35 PM