Expert evidence of facial image comparison:Admissibility and evaluation(MLR seminar on the Reliability of Expert Evidence, Northumbria University, 12 Feb 2010) Tony Ward Experts & Institutions: Centre for the Study of Expert Knowledge in Law and Society
Common knowledge “If on the proven facts a judge or jury can form their own conclusions without help, then the opinion of an expert is unnecessary.” (Turner 1975) Jurors competent to recognise faces (Dodson & Williams 1984; AG’s Ref no. 2 of 2002  1 Cr.App.R. 21) Is there a rule? Does it apply? Should it?
Applying the rule? “Where...there is a clear photograph and no suggestion that the subject has changed his appearance, a jury could usually reach a conclusion without help. Where, as here...the appellant had grown a beard shortly before his arrest, and ...the robber may have been wearing clear spectacles and a wig for disguise...expert evidence ....can provide the jury with information and assistance they would otherwise lack...” (Stockwell (1993) 97 Cr. App. R. 260) If the “real evidence is not sufficiently intelligible to the jury without expert evidence, it has always been accepted that it is possible to place before the jury the opinion of an expert in order to assist them in their interpretation of the real evidence.” (Clarke  2 Cr. App. R. 425) But admissible as a matter of convenience? (Nugent  EWCA Crim 3434)
Should the rule apply? Turner concerned with mental states – interpretation of observed facts in light of folk psychology. ‘Encoding’ unfamiliarfaces and comparing them with photographs is difficult (Davies & Thasen 2000; Costigan 2007) Jury needs all the help it can get – provided it’s reliable!
Reliability: Ciantar EWCA Crim 3559 “Could not be suggested” that facial mapping not a body of knowledge sufficiently recognised to be reliable (Bonython/Luttrell test) Judge “must determine whether the evidence is such as to entitle the jury to consider it. Thus if there is expert evidence capable of acceptance it is not for the judge to withdraw it from the jury merely because there is other evidence which contradicts it.”
Reliability: Atkins  EWCA Crim 1786 “Courts need to be scrupulous to ensure that evidence proffered as expert, for any party, is indeed based upon specialised experience, knowledge or study. Mere self-certification, without demonstration of study, method and expertise, is by itself not sufficient. … The three principal remedies [for overstatement of probative value] are (i) to have such evidence examined and, if appropriate, criticised by an expert of equal experience and skill, (ii) to subject the evidence to rigorous testing in the witness box and (iii) to ensure careful judicial exposition to the jury of the difference between factual examination/comparison or arithmetical measure on the one hand and, on the other, a subjective, but informed, judgment of the significance of the findings.”
Is this enough? No! Yes! Most evidence, taken in isolation, is unreliable (esp. identification) – why should expert evidence be different? Hard to assess but so is lay identification • ‘Specialised experience, knowledge or study’ doesn’t guarantee even minimal reliability • Heavy reliance on knowledge, resources and motivation of defence lawyers (and candour of expert)
Compromise solutions • Modified ‘ultimate issue’ rule – expert to help jury examine real evidence but not draw conclusions (Gray) • Facial recognition evidence alone normally/always insufficient to convict • contrary to Hookway EWCA Crim 212, BAILLII • Warning to jury of dangers of over-reliance
Ultimate issue rule • Wright (1821) – doubt as to admissibility of conclusions drawn from same evidence the jury heard • ‘a matter of form rather than substance’ • Stockwell (1993) 97 Cr. App. R. 260, followed in Atkins • Gray  EWCA Crim 1001: evidence of similarities admissible but ‘strong support’ inadmissible without means of calculating probabilities • Not followed in Gardner  EWCA Crim 1639, Mitchell  EWCA Crim 731 or Atkins
Against the ‘rule’ “An expert who spends years studying this kind of comparison can properly form a judgment as to the significance of what he has found in any particular case. It is a judgment based on his experience. A jury is entitled to be informed of his assessment. The alternative, of simply leaving the jury to make up its own mind about the similarities and dissimilarities, with no assistance at all about their significance, would be to give the jury raw material with no means of evaluating it.” (Atkins 2009) Would also restrict cautious evaluations of significance of similarities (ibid.)
No case to answer? • Weight a matter for the jury (Atkins; Reed  EWCA Crim 2698) • But no case for answer unless evidence “taken at its highest” could make “reasonable jury, properly directed” sure of guilt (Galbraith). • Distinction between judgements of credibility and reliability: Daley v. R  1 AC 117, 128. • Can reasonable jury take expert as reliable enough to convict without independent evidence of validity of expert’s technique?
Applying Galbraith • Buckland  EWCA Crim 1639: • weak lay ID + “strong support” + lie = no case to answer • Mulgrew EWCA Crim 1375: • “it was as plain as a pikestaff that there were general similarities between the man shown in the photograph and the man which P.C. Whittaker purported to recognise. It added nothing to the recognition of the officer to say or assert whether as an expert or otherwise that the appellant could not be eliminated as a candidate” • Court accepts each expert’s evaluation of the strength of his own evidence (i.e. ultimate issue)
Hookway (1999) “The evidence …consisted solely of expert evidence of so-called ‘facial mapping.’” Mr Neave “said he could not say for definite that the robber and the appellant were the same person; facial mapping was not the same as a fingerprint. He conceded that, if a trawl were made through Manchester, it might be possible to find one or two other people of similar appearance.” “…he could not say, with absolute certainty, 100 percent, that the offender was the appellant. But, he … set out, for the jury's consideration, the detail of his observations which lent support to his conclusion.”
Hookway (1999) • Galbraith – on whatbasis could a reasonable jury be sure? • Prosecutor’s fallacy? Prior odds ≥ male pop of Manchester • Moral prejudice? • “… having regard to that which transpired thereafter, there could not be any ground…for regarding the conviction as being in any way unsafe.” • “Detail of observations” at most shows plausible hypothesis • But can it be worse than lay identification of strangers?
Warnings “It is important that you should be cautious in your approach to evidence which claims to make an identification to a high degree of probability… an honest witness who is mistaken can be very persuasive or can appear to be very persuasive.” – Trial judge in Gardner (2004) “…the fact that a conclusion is not based upon a statistical database recording the incidence of the features compared as they appear in the population at large needs to be made crystal clear to the jury.” (Atkins, 2009 at ) “…it may help the jury for the judge to explain that the forms of expression are labels applied by the witness to his opinion of the significance of his findings and different experts may not attach the same label to the same degree of comparability.” (Atkins at )
A proposal • Treat like identification under Turnbull/Devlin Report (applied to experts in Luttrell  EWCA Crim 1344) • Judge to warn of dangers but also direct jury to consider any factors that could make them sure • Specific to faces: e.g. image quality; camera angles; database; foils? • Relevant to experts in general: e.g. proficiency testing, peer review • If no such factors and little/no other evidence, direct acquittal. • Equivalent to admissibility in practice? • But allows relatively weak evidence for defence or as limited support for prosecution case (Davies  EWCA Crim 2521)