EvidenceProf Blog

Editor: Colin Miller
Univ. of South Carolina School of Law

Wednesday, April 9, 2008

Article of Interest: Professor Sandra Guerra Thompson's Beyond a Reasonable Doubt?: Reconsidering Uncorroborated Eyewitness Identification Testimony

I highly recommend Beyond a Reasonable Doubt?: Reconsidering Uncorroborated Eyewitness Identification Testimony, the new article by University of Houston Law Center Professor Sandra Guerra Thompson, which will be published in an upcoming issue of the UC Davis Law Review.  The article's argument is that there should be a corroborating evidence requirement for eyewitness identifications.

In Part I, Professor Thompson notes that countless psychological experiments and field studies have concluded that eyewitnesses inevitably err in their recollections of events and persons.  There are two categories of variables that contribute to this likelihood of error:  estimator variables and system variables.  Estimator variables are variables that cannot be addressed by the legal system.  They include the lighting conditions at the time the event or person was percieved, whether the identification is cross-racial (which decreases the accuracy of IDs), whether the event perceived was violent (which also decreases accuracy), and unconscious transference (when a person seen in one situation is mistakenly remembered by a witness as being seen in a different situation).  Meanwhile, the two principal system variables are: (1) the possibility that police investigators can use conscious or unconscious suggestion to encourage eyewitnesses to choose the suspect arrested by police, and (2) the possibility that an eyewitness makes an identification based upon "relative judgment," a psychological process which causes a witness to select the person in a line-up who best fits the limited contours of the witness's memory, rather than choosing solely on the basis of independent memory.

In Part II, Professor Thompson argues that these problems have contributed to many individuals being wrongfully convicted based upon eyewitness testimony and that none of the remedies implemented to address these problems has even the potential to counteract the frequent inaccuracy introduced by eyewitness identification testimony.  The first is the right to counsel at police line-ups, which is  underutilized because it is limited to line-ups conducted after the initiation of formal proceedings against the accused and because it does not apply at all to IDs from photo spreads.  The second is the exclusion of IDs made under "unduly suggestive" circumstances, which is inefficacious because it requires police misconduct and fails to address estimator variables.  The third is the use of expert testimony and special jury instructions designed to educate the jury on the scientific knowledge on the effect of certain factors on identification accuracy; however, for decades, judges had precluded the use of such testimony and instructions.  The fourth is the proposed use of "blind" line-ups and photo-arrays, in which the police investigator does not know the identity of the suspect arrested by the police, and the sequential line-up, in which individuals are presented one at a time.  The problem with these techniques is that there is little reason to expect that they will be adopted on a wide-scale basis and, once again, they only address system variables, not estimator variables.  And as Professor Thompson notes, there is little scientific basis for believing that system variables account for the lion's share of inaccuracies.

Because Professor Thompson finds these remedies inadequate, she argues in Part III that the American justice system should not allow for a defendant to be convicted based solely on the identification testimony of one eyewitness and that instead there should be a requirement of some additional identifying evidence.  She first argues that such a bright-line rule is necessary because we cannot expect to safeguard the innocent from wrongful convictions by means of trial or appellate remedies that require courts to exercise their discretion.  She next contends that such a rule has advantanes for both police and prosecutors, specifically relieving the latter from having to resolve the moral dilemma of whether to try a defendant based upon the eyewitness testimony of a sole witness.  She then notes that her recommendation has historical support as corroboration requirements have perhaps the longest lineage of all evidentiary rules.

Professor Thompson concludes by arguing that her proposed rule could be adopted as a rule of criminal procedure, either by legislative initiative, by state high court decisions interpreting state constitutional law, or by the U.S. Supreme Court as a matter of federal constitutional law.  She then notes that there should be exception to the rule where the eyewitness had a pre-existing relationship with the defendant and addresses some potential criticisms to the proposal.

I have read numerous studies on the unreliable of eyewitness identifications and recommend the many studies cited in Professor Thompson's article.  And based upon those studies, I strongly agree with the recommendation made in Professor Thompson's article and think she does a tremendous job of advocating for the new rule in an even handed manner.  I e-mailed Professor Thompson about what led her to write the article, and she responded:

"In my criminal procedure class one day, we studied some of the psychology literature outlining the inherent failings of witnesses' perception and memory that often lead to erroneous eyewitness identifications.  We noted that the circumstances under which we usually ask witness to make identifications--after being victims of violent crimes--are those in which perception and memory are least likely to function accurately.  The discussion led one of my students to ask afterward how a jury could be allowed to convict "beyond a reasonable doubt" based only on such unreliable evidence.  I realized immediately that the student was right, no conviction should be allowed to rest solely on uncorroborated eyewitness identification testimony unless the witness and victim have a prior relationship.  Otherwise, the evidence should be viewed by law to be too unreliable to alone support a

So I set out to learn more about the psychological literature that focuses on the powers of perception and memory, in addition to the influences that can be brought to bear by police investigators.  My piece fills a gap in the list of remedies currently proposed by Innocence Commissions and activist organizations around the country. Most proposed reforms in the area of eyewitness identification have focused, quite naturally, on the conditions that the legal system can try to improve, namely the procedures followed by police investigators. My article focuses on preventing wrongful convictions by legally recognizing the inherent fallibility of crime victims' powers of perception and memory and simply requiring additional proof for conviction.  I delve deeply into the history of corroborating evidence requirements in making my case.  Corroborating evidence requirements have a bad reputation because of their past notorious use in rape trials. Overall, however, the history of such requirements put them on par with exclusionary rules as a means of preventing miscarriages of justice based on unreliable evidence.  This historical analysis of corroborating evidence rules is a feature of the piece that I believe
makes a new contribution to the evidence literature."



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