Opinion ID: 1173314
Heading Depth: 2
Heading Rank: 1

Heading: Expert Testimony on Eyewitness Identification

Text: (1a) Defendant contends the court abused its discretion in excluding the testimony of an expert witness on the psychological factors that may affect the accuracy of eyewitness identification. Prior to trial the defense moved for an order admitting the testimony of Dr. Robert Shomer. (Evid. Code, § 402.) Dr. Shomer is a practicing psychologist and professor of psychology of almost 20 years' experience. He has taught numerous courses on the psychology of perception, memory, and recall, and has spoken and written frequently on such topics in both medical and legal settings. He is conversant with the scientific literature on the psychology of eyewitness identification, has done experimental research on the subject himself, and has published articles on that research. He has qualified as an expert psychological witness in more than two dozen state and federal trials. The People do not question the witness' qualifications. At the hearing on the motion Dr. Shomer explained that he proposed to inform the jury of various psychological factors that may affect the reliability of eyewitness identification, and to help to counter some common misconceptions about the process. He noted first that all eyewitness identification begins with the observer's initial perception of the event. The physical circumstances affecting that observation are generally known to laymen, such as lighting, distance, and duration. But psychological factors may also influence the accuracy of the perception: Dr. Shomer intended to review for the jury the results of certain experimental studies showing that perception may be affected by such factors as the observer's state of mind, his expectations, his focus of attention at the time, the suddenness of the incident, the stressfulness of the situation, and differences in the race and/or age of the observer and the observed. On the latter point he would have testified, for example, that there are substantial decreases in accuracy when the two persons are of different races or ages. The next phase of the process is memory. Dr. Shomer intended to discuss with the jury the evidence showing that memory is not merely a passive recording event, producing an imperishable reproduction of the scene perceived; rather, it is both a selective and a constructive process, in which old elements fade and are lost while new elements  subsequent information or suggestions  are unconsciously interwoven into the overall recollection until the subject cannot distinguish one from the other. [7] The last step is retrieval. Dr. Shomer proposed to review the studies establishing that recall may be affected by such factors as the subject's expectations, his suggestibility, the phrasing of the questions asked of him, and even the size and type of the photographs he is shown. For example, Dr. Shomer would have explained to the jury that witnesses who are asked to identify criminals in lineups or photo displays tend to find the experience psychologically unpleasant and wish to terminate it. Because of this self-induced pressure, such witnesses may subconsciously take a simple request to point out the offender if he is in the lineup and convert it into a demand that they find the face in the lineup that is the most similar to the offender; that alternative appears more legitimate to them than admitting they cannot identify anyone at all. Turning to the case at bar, Dr. Shomer made it clear that he did not propose to offer an opinion that any particular witness at this trial was or was not mistaken in his or her identification of defendant. But he did intend to point out various psychological factors that could have affected that identification in the present case. Thus he emphasized that from the viewpoint of the witnesses the shooting of Esparza on a busy streetcorner was a sudden and unexpected event, occurring some distance away, and that because of parked and passing cars their observations were largely discontinuous. He also referred to the youth of certain of the witnesses, the words used in making the pretrial photographic identifications of defendant, and the ambiguity of those identifications. Dr. Shomer particularly noted the effect of the cross-racial factor in this case, emphasizing that the one witness who was certain that defendant, a black, was not the black man at the scene was herself a black (Waller); by contrast, two of the witnesses who positively identified defendant at trial as the assailant (Molinar and Iglesias) were of the same ethnic origin (Hispanic) as the victim. Finally, Dr. Shomer intended to explain to the jury that empirical research has undermined a number of widespread lay beliefs about the psychology of eyewitness identification, e.g., that the accuracy of a witness's recollection increases with his certainty, that accuracy is also improved by stress, that cross-racial factors are not significant, and that the reliability of an identification is unaffected by the presence of a weapon or violence at the scene. On this showing, defendant offered the testimony of Dr. Shomer as an aid to the jurors in weighing the eyewitness identifications in this case. The People objected on the sole ground that to admit the testimony would usurp the jury's function, citing People v. Johnson (1974) 38 Cal. App.3d 1, 6-7 [112 Cal. Rptr. 834], and similar decisions. [8] The trial court, conceding that it was the first time it had encountered this type of evidence, ruled the testimony inadmissible. The court declared that it fully agreed with the reasoning of Johnson : observing that none of the prosecution witnesses have psychological defects, the court concluded that to allow Dr. Shomer to testify would be invading the province of the jury. Defendant protested that Dr. Shomer would not give an opinion on the credibility of any particular witness, but would simply provide the jurors with information to help them determine the accuracy of the various identifications put before them. The court stood by its ruling, adding the further grounds that it intended to give a standard instruction on discrepancies in testimony (CALJIC No. 2.21 (4th ed. 1979)), that expert testimony on eyewitness identification maybe would have a tendency to maybe cause confusion in the jurors' minds, and that such testimony is really not what I consider scientific enough at this point in time to be admissible.
The United States Supreme Court has recognized that The vagaries of eyewitness identification are well-known; the annals of criminal law are rife with instances of mistaken identification. ( United States v. Wade (1967) 388 U.S. 218, 228 [18 L.Ed.2d 1149, 1158, 87 S.Ct. 1926].) The court noted the high incidence of miscarriage of justice caused by such mistaken identifications, and warned that the dangers for the suspect are particularly grave when the witness' opportunity for observation was insubstantial, and thus his susceptibility to suggestion the greatest. ( Id. at pp. 228-229 [18 L.Ed.2d at pp. 1158-1159].) Distinguished federal judges have echoed and amplified these warnings. Thus in Jackson v. Fogg (2d Cir.1978) 589 F.2d 108, the court upheld an order vacating a robbery-murder conviction on habeas corpus because prelineup procedures were unduly suggestive and because the four eyewitnesses had only a brief opportunity to observe the gunman under stressful conditions and showed varying degrees of certainty in their identifications of the defendant. There was no other evidence connecting the defendant with the crime. Writing for a unanimous court, Judge Lumbard observed that Centuries of experience in the administration of criminal justice have shown that convictions based solely on testimony that identifies a defendant previously unknown to the witness is highly suspect. Of all the various kinds of evidence it is the least reliable, especially where unsupported by corroborating evidence. ( Id. at p. 112.) Some of the reasons for that unreliability were discussed by Judge (later Solicitor General) McCree in United States v. Russell (6th Cir.1976) 532 F.2d 1063, 1066: There is a great potential for misidentification when a witness identifies a stranger based solely upon a single brief observation, and this risk is increased when the observation was made at a time of stress or excitement.... [T]his danger is inherent in every identification of this kind, .... As Judge McCree noted, This problem is important because of all the evidence that may be presented to a jury, a witness' in-court statement that `he is the one' is probably the most dramatic and persuasive. ( Id. at p. 1067.) The rule that the testimony of a single witness is sufficient to prove identity (see Evid. Code, § 411) is premised in part on the assumption that an eyewitness identification is generally reliable. Yet Judge Hufstedler has declared that premise to be at best, highly dubious, given the extensive empirical evidence that eyewitness identifications are not reliable. ( United States v. Smith (9th Cir.1977) 563 F.2d 1361, 1365 (conc. opn.).) And with his characteristic vigor, Chief Judge Bazelon has called on the courts to face up to the reliability problems of eyewitness identification, to inform themselves of the results of scientific studies of those problems, and to allow juries access to that information in aid of their factfinding tasks. ( United States v. Brown (D.C. Cir.1972) 461 F.2d 134, 145-146, fn. 1 (conc. & dis. opn.).) [9] In the dozen years since Judge Bazelon's appeal, empirical studies of the psychological factors affecting eyewitness identification have proliferated, and reports of their results have appeared at an ever-accelerating pace in the professional literature of the behavioral and social sciences. No less than five treatises on the topic have recently been published, citing and discussing literally scores of studies on the pitfalls of such identification. (Eyewitness Testimony: Psychological Perspectives (Wells & Loftus edits. 1984) [hereinafter Eyewitness Testimony: Psychological Perspectives]; Evaluating Witness Evidence: Recent Psychological Research and New Perspectives (Lloyd-Bostock & Clifford edits. 1983); Sobel, Eyewitness Identification: Legal and Practical Problems (2d ed. 1983); Loftus, Eyewitness Testimony (1979); Yarmey, The Psychology of Eyewitness Testimony (1979); see also Johnson, Cross-Racial Identification Errors in Criminal Cases (1984) 69 Cornell L.Rev. 934 [hereinafter Cross-Racial Identification Errors ]; Note, Did Your Eyes Deceive You? Expert Psychological Testimony on the Unreliability of Eyewitness Identification (1977) 29 Stan. L.Rev. 969 [hereinafter Expert Psychological Testimony ].) Indeed, in 1984 two leading researchers estimated that on this topic over 85% of the entire published literature has surfaced since 1978. (Wells & Loftus, Eyewitness Research: Then and Now, in Eyewitness Testimony: Psychological Perspectives, p. 3.) The consistency of the results of these studies is impressive, and the courts can no longer remain oblivious to their implications for the administration of justice.
A traditional way of bringing scientific information to the attention of the judicial system, of course, is by the testimony of expert witnesses. But when that testimony relates to psychological factors affecting the accuracy of eyewitness identification, the courts have shown reluctance to admit it: appellate decisions almost unanimously hold that rulings excluding such evidence do not constitute an abuse of discretion. (See, e.g., Com. v. Francis (1983) 390 Mass. 89 [453 N.E.2d 1204, 1207-1208], and cases cited.) We inquire whether that reluctance remains justified. [10] This court has not previously addressed the admissibility of expert testimony on eyewitness identification. Several opinions of the Court of Appeal discuss the issue, but on close analysis none appears satisfactory. The leading case in this state  followed by the trial court in the case at bar  is People v. Johnson, supra, 38 Cal. App.3d 1. There the sole evidence connecting the defendants with a robbery-murder at a liquor store was the eyewitness identification of the surviving robbery victims. The defense sought to discredit that identification on various grounds, including the offer of expert testimony by a psychologist as to the ability of eyewitnesses to accurately perceive, remember and relate, and the distorting effects of excitement and fear on those functions. The trial court excluded the testimony, and the Court of Appeal upheld the ruling on four grounds. None, however, is immune from criticism. First, the opinion reasons that although Evidence Code section 780, subdivision (c), permits a witness to be impeached by discrediting his capacity to perceive, recollect or communicate, it does not follow that a party has a right to impeach a witness by calling another witness to testify as to the former's capacity. (38 Cal. App.3d at p. 6.) The argument misses the point. The expert witness in Johnson  just as Dr. Shomer here  would not have testified that any particular prosecution witness lacked the capacity to perceive, remember and relate; rather, he would simply have informed the jury of certain psychological factors that may impair the accuracy of a typical eyewitness identification, including the emotions of excitement or fear, with supporting references to experimental studies of such phenomena. (2) Such evidence falls well within the broad statutory description of any matter that has any tendency in reason to bear on the credibility of a witness. (Evid. Code, § 780.) (3) Second, the Johnson opinion states that Evidence Code section 801, subdivision (a), limits expert testimony to subjects beyond the range of common experience (38 Cal. App.3d at pp. 6-7). This paraphrase of the statutory scheme, however, is both incomplete and misleading. To begin with, by its terms section 801 applies only to expert testimony in the form of an opinion. If an expert testifies not as to his opinion but as to facts within his special knowledge, section 801 is inapplicable. Factual testimony by an expert is admissible if it complies with the general statutory requirements that the witness be qualified by his special knowledge (Evid. Code, § 720) and that his evidence be relevant to the issues ( id., § 351). [11] Much of the proposed testimony of the psychologist in Johnson and of Dr. Shomer here would have related primarily to matters of fact: the contents of eyewitness identification studies reported in the professional literature  their methodology, their data, and their findings  are facts, verifiable by anyone who can read and understand the studies in question. [12] In any event, to the extent these cases may involve opinion testimony by the psychologist witness, the Johnson paraphrasing of section 801, subdivision (a), errs by omission. The statute does not flatly limit expert opinion testimony to subjects beyond common experience; rather, it limits such testimony to such subjects  sufficiently beyond common experience that the opinion of an expert would assist the trier of fact  (italics added). The emphasized words, omitted by the Johnson court, make it clear that the admissibility of expert opinion is a question of degree. The jury need not be wholly ignorant of the subject matter of the opinion in order to justify its admission; if that were the test, little expert opinion testimony would ever be heard. Instead, the statute declares that even if the jury has some knowledge of the matter, expert opinion may be admitted whenever it would assist the jury. It will be excluded only when it would add nothing at all to the jury's common fund of information, i.e., when the subject of inquiry is one of such common knowledge that men of ordinary education could reach a conclusion as intelligently as the witness ( People v. Cole (1956) 47 Cal.2d 99, 103 [301 P.2d 854, 56 A.L.R.2d 1435]). (1b) We apply this test to expert testimony on eyewitness identification. It is doubtless true that from personal experience and intuition all jurors know that an eyewitness identification can be mistaken, and also know the more obvious factors that can affect its accuracy, such as lighting, distance, and duration. [13] It appears from the professional literature, however, that other factors bearing on eyewitness identification may be known only to some jurors, or may be imperfectly understood by many, or may be contrary to the intuitive beliefs of most. For example, in the case at bar Dr. Shomer would have testified to the results of studies of relevant factors that appear to be either not widely known to laypersons or not fully appreciated by them, such as the effects on perception of an eyewitness' personal or cultural expectations or beliefs (see Loftus, Eyewitness Testimony (1979) pp. 36-48), the effects on memory of the witness' exposure to subsequent information or suggestions ( id. at pp. 54-87), and the effects on recall of bias or cues in identification procedures or methods of questioning ( id. at pp. 89-99; see generally Hall et al., Postevent Information and Changes in Recollection for a Natural Event, in Eyewitness Testimony: Psychological Perspectives, pp. 124-141). Dr. Shomer would also have explained to the jury the pitfalls of cross-racial identification, evidently an important factor on the record in this case. To be sure, many jurors are likely to have some awareness of the fact that an eyewitness is more accurate in identifying a person of his own race than one of another race. (See, e.g., People v. Dixon (1980) 87 Ill. App.3d 814 [410 N.E.2d 252, 256].) But it appears that few jurors realize the pervasive and even paradoxical nature of this own-race effect, information that has emerged from numerous empirical studies of the question. These studies establish that the effect is strongest when white witnesses attempt to recognize black subjects; in such circumstances The impairment in ability to recognize black faces is substantial. ( Cross-Racial Identification Errors, pp. 938-939.) [14] In laboratory experiments, for example, it is common for own-race/other-race recognition rates to differ by as much as 30 percent. ( Id. at pp. 942-943.) The studies also reveal two aspects of the matter that will probably be contrary to most jurors' intuitions: first, that white witnesses who are not racially prejudiced are just as likely to be mistaken in making a cross-racial identification as those who are prejudiced; and second, that white witnesses who have had considerable social contact with blacks may be no better at identifying them than those who have not. ( Id. at pp. 943-944.) Finally, some jurors may deny the existence of the own-race effect in the misguided belief that it is merely a racist myth exemplified by the derogatory remark, they all look alike to me, while others may believe in the reality of this effect but be reluctant to discuss it in deliberations for fear of being seen as bigots. ( Id. at p. 969; see also Wells, A Reanalysis of the Expert Testimony Issue, in Eyewitness Testimony: Psychological Perspectives, p. 309.) In addition to the foregoing counterintuitive aspects of the own-race effect, other psychological factors have been examined in the literature that appear to contradict the expectations of the average juror. Perhaps the foremost among these is the lack of correlation between the degree of confidence an eyewitness expresses in his identification and the accuracy of that identification. Numerous investigations of this phenomenon have been conducted: the majority of recent studies have found no statistically significant correlation between confidence and accuracy, and in a number of instances the correlation is negative  i.e., the more certain the witness, the more likely he is mistaken. (Wells & Murray, Eyewitness Confidence, in Eyewitness Testimony: Psychological Perspectives, pp. 159-162.) Indeed, the closer a study comes to reproducing the circumstances of an actual criminal investigation, the lower is that correlation ( id. at pp. 162-165), leading the cited authors to conclude that the eyewitness accuracy-confidence relationship is weak under good laboratory conditions and functionally useless in forensically representative settings. ( Id. at p. 165; see also Deffenbacher, Eyewitness Accuracy and Confidence: Can We Infer Anything About Their Relationship? (1980) 4 Law & Human Behav. 243.) The average juror, however, remains unaware of these findings: A number of researchers using a variety of methods have found that people intuitively believe that eyewitness confidence is a valid predictor of eyewitness accuracy. (Wells & Murray, supra, at p. 159, citing five recent studies.) (4) We conclude that although jurors may not be totally unaware of the foregoing psychological factors bearing on eyewitness identification, the body of information now available on these matters is sufficiently beyond common experience that in appropriate cases expert opinion thereon could at least assist the trier of fact (Evid. Code, § 801, subd. (a)). [15] The third ground of the Johnson opinion is premised on its observation (38 Cal. App.3d at p. 7) that In cases not involving sex offenses California courts usually reject attempts to impeach a witness by means of psychiatric testimony, citing Ballard v. Superior Court (1966) 64 Cal.2d 159, 172 [49 Cal. Rptr. 302, 410 P.2d 838, 18 A.L.R.3d 1416]. Ballard held (at pp. 173-175) that in a sex offense case expert medical testimony of a psychiatrist may be admitted to impeach the credibility of the complaining witness by showing that she suffers from a particular physical or mental illness or disorder that impairs her ability to tell the truth. (See also People v. Russel (1968) 69 Cal.2d 187, 193, 195-196 [70 Cal. Rptr. 210, 443 P.2d 794].) The Johnson opinion then reasons (38 Cal. App.3d at p. 7) that The present occurrence was frightening but hardly deranging. There is no evidence or claim of emotional disturbance or psychological `abnormality' of any of the prosecution witnesses. Again the argument misses the point. In neither Johnson nor the case at bar did the defense offer expert medical testimony by a psychiatrist to attack the truth-telling ability of any witness. The Ballard rule therefore has nothing to do with the case, and it is totally irrelevant that these are cases not involving sex offenses or that no witness was shown to be abnormal. Fourth, the Johnson opinion ( ibid. ) also upholds the trial court's ruling on the ground that to admit expert psychological evidence on eyewitness identification would take over the jury's task of determining the weight and credibility of the witness' testimony  or, to put it in the more colorful language of legal cliche used by many courts, would invade the province or usurp the function of the jury, because such evidence embraces the ultimate issue. As Dean Wigmore has said, however, such language is so misleading, as well as so unsound, that it should be entirely repudiated. It is a mere bit of empty rhetoric, and remains simply one of those impracticable and misconceived utterances which lack any justification in principle. (Fns. omitted.) (7 Wigmore on Evidence (Chadbourn rev. ed. 1978), § 1920, p. 18, § 1921, p. 22.) Specifically referring to expert psychological evidence on eyewitness identification, the author of a leading treatise on the topic asserts that the objection based upon the `province of the jury' is no more than a shibboleth which, if accepted, would deprive the jury of important information useful and perhaps necessary for a proper decision on a difficult issue. (Wall, Eye-Witness Identification in Criminal Cases (1965) p. 213.) (1c) The reasons for these criticisms are several. The expert testimony in question does not seek to take over the jury's task of judging credibility: as explained above, it does not tell the jury that any particular witness is or is not truthful or accurate in his identification of the defendant. Rather, it informs the jury of certain factors that may affect such an identification in a typical case; and to the extent that it may refer to the particular circumstances of the identification before the jury, such testimony is limited to explaining the potential effects of those circumstances on the powers of observation and recollection of a typical eyewitness. The jurors retain both the power and the duty to judge the credibility and weight of all testimony in the case, as they are told by a standard instruction. [16] Nor could such testimony in fact usurp the jury's function. As is true of all expert testimony, the jury remains free to reject it entirely after considering the expert's opinion, reasons, qualifications, and credibility. Indeed, the Penal Code commands (§ 1127b) that an instruction so informing the jury be given in any criminal trial in which expert opinion evidence is received. [17] Finally, California has abandoned the ultimate issue rule in any event: in this state we have followed the modern tendency and have refused to hold that expert opinion is inadmissible merely because it coincides with an ultimate issue of fact. ( People v. Cole, (1956) supra, 47 Cal.2d 99, 105, and cases cited.) Evidence Code section 805 codifies this case law, declaring that Testimony in the form of an opinion that is otherwise admissible is not objectionable because it embraces the ultimate issue to be decided by the trier of fact. [18]
For the reasons stated, the challenged ruling excluding the expert testimony of Dr. Shomer is not supported by the trial court's professed agreement with the reasoning of Johnson, or by its observation that the prosecution witnesses have no psychological defects (i.e., the Ballard rule), or by its flat assertion that such expert testimony would invade the province of the jury. Nor is the ruling supported by the court's announced intent to give the standard instruction on discrepancies in testimony. (CALJIC No. 2.21 (4th ed. 1979).) The instruction contains only a few general remarks on the topic; [19] it does not even begin to convey to the jury the specific data on the eyewitness identification process that Dr. Shomer's testimony would have provided, a task that in any event is beyond the function of instructions. (Pen. Code, § 1127 [Either party may present to the court any written charge on the law, but not with respect to matters of fact].) Nor, again, is the ruling supported by the court's speculation that this testimony might tend to confuse the jurors. (5) Evidence that is relevant to the prime theory of the defense cannot be excluded in wholesale fashion merely because the trial would be simpler without it. Rather, it should be accompanied by instructions clearly explaining to the jury the purpose for which it is introduced. As noted above (fn. 11, ante ), any excess in the quantity or complexity of such testimony can be controlled by the court's power to limit the presentation of evidence. (1d) Lastly, the ruling is not supported by the court's opinion that expert testimony on eyewitness identification is not yet scientific enough to be admissible. The court illustrated its point by referring to the general rule excluding lie-detector evidence. (See, e.g., People v. Wochnick (1950) 98 Cal. App.2d 124, 127-128 [219 P.2d 170].) The choice of words and example makes it clear the court was implicitly invoking the Kelly-Frye rule, i.e., the rule that evidence based on a new scientific method of proof is admissible only on a showing that the procedure has been generally accepted as reliable in the scientific community in which it developed. ( People v. Kelly (1976) 17 Cal.3d 24 [130 Cal. Rptr. 144, 549 P.2d 1240]; Frye v. United States (D.C. Cir.1923) 293 F. 1013 [34 A.L.R. 145].) We are not persuaded, however, that the Kelly-Frye rule applies to expert testimony on eyewitness identification. (See Cross-Racial Identification Errors, p. 971; Expert Psychological Testimony, pp. 1021-1023.) It is important to distinguish in this regard between expert testimony and scientific evidence. When a witness gives his personal opinion on the stand  even if he qualifies as an expert  the jurors may temper their acceptance of his testimony with a healthy skepticism born of their knowledge that all human beings are fallible. But the opposite may be true when the evidence is produced by a machine: like many laypersons, jurors tend to ascribe an inordinately high degree of certainty to proof derived from an apparently scientific mechanism, instrument, or procedure. Yet the aura of infallibility that often surrounds such evidence may well conceal the fact that it remains experimental and tentative. ( People v. Kelly, supra, at p. 32, and cases cited.) For this reason, courts have invoked the Kelly-Frye rule primarily in cases involving novel devices or processes such as lie detectors, truth serum, Nalline testing, experimental systems of blood typing, voice-prints, identification by human bite marks, microscopic analysis of gunshot residue, and hypnosis ( People v. Shirley (1982) 31 Cal.3d 18, 51-54 [181 Cal. Rptr. 243, 641 P.2d 775], and cases cited), and, most recently, proof of guilt by rape trauma syndrome ( People v. Bledsoe (1984) 36 Cal.3d 236, 246-251 [203 Cal. Rptr. 450, 681 P.2d 291]). In some instances the evidence passed the Kelly-Frye test, in others it failed; but in all such cases the rule serves its salutary purpose of preventing the jury from being misled by unproven and ultimately unsound scientific methods. ( Shirley, supra, at p. 53.) Here, by contrast, no such methods are in issue. We have never applied the Kelly-Frye rule to expert medical testimony, even when the witness is a psychiatrist and the subject matter is as esoteric as the reconstitution of a past state of mind or the prediction of future dangerousness, or even the diagnosis of an unusual form of mental illness not listed in the diagnostic manual of the American Psychiatric Association ( People v. Phillips (1981) 122 Cal. App.3d 69, 86-87 [175 Cal. Rptr. 703] (Munchausen's syndrome by proxy)). We see no reason to require a greater foundation when the witness is a qualified psychologist who will simply explain to the jury how certain aspects of everyday experience shown by the record can affect human perception and memory, and through them, the accuracy of eyewitness identification testimony. Indeed, it would be ironic to exclude such testimony on Kelly-Frye grounds on the theory that jurors tend to be unduly impressed by it, when jurors are far more likely to be unduly impressed by the eyewitness testimony itself.
(6) It remains true, of course, that Where expert opinion evidence is offered, much must be left to the discretion of the trial court ( People v. Cole, supra, 47 Cal.2d 99, 105). Yet that discretion is not absolute: in various contexts it has been held that trial courts committed reversible error in excluding expert testimony. (E.g., Brown v. Colm (1974) 11 Cal.3d 639, 647 [114 Cal. Rptr. 128, 522 P.2d 688]; People ex rel. Dept. Pub. Wks. v. Douglas (1971) 15 Cal. App.3d 814, 820-822 [93 Cal. Rptr. 644]; Varas v. Barco Mfg. Co. (1962) 205 Cal. App.2d 246, 259-261 [22 Cal. Rptr. 737]; Reynolds v. Natural Gas Equipment, Inc. (1960) 184 Cal. App.2d 724, 739-740 [7 Cal. Rptr. 879]; Burch v. Valley Motor Lines, Inc. (1947) 78 Cal. App.2d 834, 840-844 [179 P.2d 47].) A recent decision of the Arizona Supreme Court illustrates the kind of case in which the exclusion of expert testimony on psychological factors affecting eyewitness identification is a prejudicial abuse of discretion. ( State v. Chapple (1983) 135 Ariz. 281 [660 P.2d 1208].) There the defendant was convicted of three counts of first degree murder. No direct or circumstantial evidence of any kind connected him with the crime other than the testimony of two eyewitnesses, and neither eyewitness had ever seen him before the events in question. The witnesses observed the crimes being committed, inter alia, by a man who had been introduced to them as Dee. A few days later they were shown groups of photographs of acquaintances of a known participant. One of the witnesses tentatively identified a certain James Logan as Dee; although the defendant's photograph was in another of the displays, the witness did not identify it. More than a year later the witness was shown a further display that included a photograph of the defendant but none of Logan, and he identified the defendant as Dee; he was then shown the photograph of the defendant that he had previously failed to identify, but said he had no recollection of having seen it before. The other eyewitness then identified the defendant as Dee from the later display, and both witnesses positively identified the defendant at trial. The defendant presented seven witnesses who testified he was in another state on the date of the crimes. He also called psychologist Elizabeth Loftus, a nationally known expert on perception and memory, to testify to various psychological factors shown by the record that can affect the accuracy of eyewitness identification. [20] The trial court excluded this testimony on the grounds that the information it sought to convey was within the common knowledge of the jurors and would be covered in cross-examination and closing arguments. The Arizona Supreme Court recognized that the admissibility of such testimony was in the first instance a matter of trial court discretion, but held that such discretion was abused on the record before it. The court began by rejecting claims that the testimony of Dr. Loftus would have invaded the province of the jury, and pointed to an Arizona rule of evidence identical to our Evidence Code section 805. ( Id. at p. 1219.) It further rejected claims that Dr. Loftus's testimony would have been prejudicial because the jury might have given it undue weight, and that such testimony lacked probative value because it would not have included an opinion on whether the particular eyewitnesses in the case at hand were in fact mistaken in their identification. ( Ibid. ) Turning to the key question of whether Dr. Loftus's testimony was a proper subject for expert opinion, the court summarized that testimony (see fn. 20, ante ) and declined to assume that the average juror would be aware of the information it contained. ( Id. at p. 1221.) After reviewing the record, the court found that the testimony would have assisted the jury in deciding specific factual issues in the case. ( Id. at pp. 1222-1223.) Finally, the court emphasized that the facts were close, the accuracy of the eyewitness identifications was a crucial issue, and the exclusion of Dr. Loftus's testimony undercut the entire evidentiary basis of the defendant's arguments on that issue. ( Id. at p. 1222.) [21] The court concluded (at p. 1224), there were a number of substantive issues of ultimate fact on which the expert's testimony would have been of significant assistance. Accordingly, we hold that the order precluding the testimony was legally incorrect and was unsupported by the record. It was, therefore, an abuse of discretion. Holding the error to be prejudicial on the facts, the court reversed the judgment. (1e) In the case at bar a similar analysis leads to a like result. Here, too, the expert witness was undoubtedly qualified to testify on the particular matters he proposed to address. [22] Like the Arizona Supreme Court, we decline to assume that the subject matter of Dr. Shomer's testimony would have been fully known to the jurors; rather, the professional literature persuades us to the contrary. Also as in Chapple, the record establishes that Dr. Shomer's testimony would have been of significant assistance to the jury. Because no other evidence connected defendant with the crime, the crucial factor in the case was the accuracy of the eyewitness identifications. Yet on that issue the evidence was far from clear. As we noted at the outset, in the testimony of each of the witnesses who identified defendant in the courtroom there were elements that could have raised reasonable doubts as to the accuracy of the identification. These elements included the suddenness and unexpectedness of the event, discontinuity and other difficulty of observation, fear and other stress at the time of perception, overestimation of the duration of the event, feedback factors following the event, failure or uncertainty of several witnesses in selecting defendant's photograph from police displays, and, particularly important, apparent cross-racial identification discrepancies. Further doubts could have arisen from the dramatic declaration in open court by a prosecution eyewitness that defendant was not the perpetrator, and from the testimony of six witnesses that defendant was not in the state on the day the crime was committed. In these circumstances the exclusion of Dr. Shomer's testimony undercut the evidentiary basis of defendant's main line of defense  his attack on the accuracy of the eyewitness identifications  and deprived the jurors of information that could have assisted them in resolving that crucial issue. The ruling excluding such testimony was therefore unsupported by the record. We have previously shown (Part I C, ante ) that it was unsupported by the law. It follows that the ruling constituted an abuse of discretion. (7) An error in excluding expert testimony may be found harmless. (E.g., Majetich v. Westin (1969) 276 Cal. App.2d 216, 218-219 [80 Cal. Rptr. 787].) (1f) In the case at bar, however, the record compels us to conclude that the error was prejudicial. As we have seen, the issue affected by the ruling was crucial, given the absence of any other evidence connecting defendant with the crime; and the evidence on that issue was close, given the potential weaknesses in the prosecution's testimony and the presence of both eyewitness and alibi testimony favorable to the defense. [23] An error that impairs the jury's determination of an issue that is both critical and closely balanced will rarely be harmless. Rather, after an examination of the whole record we find it reasonably probable that a result more favorable to defendant would have been reached in the absence of this error. ( People v. Watson (1956) 46 Cal.2d 818, 836 [299 P.2d 243].) There has therefore been a miscarriage of justice, and the judgment must be reversed. (Cal. Const., art. VI, § 13.) (8) We reiterate that the decision to admit or exclude expert testimony on psychological factors affecting eyewitness identification remains primarily a matter within the trial court's discretion; like the court in Chapple, we do not intend to `open the gates' to a flood of expert evidence on the subject. (660 P.2d at p. 1224.) We expect that such evidence will not often be needed, and in the usual case the appellate court will continue to defer to the trial court's discretion in this matter. [24] Yet deference is not abdication. When an eyewitness identification of the defendant is a key element of the prosecution's case but is not substantially corroborated by evidence giving it independent reliability, and the defendant offers qualified expert testimony on specific psychological factors shown by the record that could have affected the accuracy of the identification but are not likely to be fully known to or understood by the jury, it will ordinarily be error to exclude that testimony.