I R v Kuba Dlugosz

JurisdictionEngland & Wales
Judgment Date30 January 2013
Neutral Citation[2013] EWCA Crim 2
Docket NumberCase No: 2011/04122/C2, 2012/03728/B1, 2012/02955/D4
CourtCourt of Appeal (Criminal Division)
Date30 January 2013

[2013] EWCA Crim 2




HHJ Gordon (Dlugosz)


HHJ Chambers QC (Pickering)


HHJ Pontius (MDS)

Royal Courts of Justice

Strand, London, WC2A 2LL


President Of The Queen's Bench Division

Lord Justice Kitchin


Mrs Justice Cox

Case No: 2011/04122/C2, 2012/03728/B1, 2012/02955/D4

I Regina
Kuba Dlugosz
II Regina
III Regina

Mr Oliver S P Blunt and Mr Hugh Blake - James for the Appellant Dlugosz

Mr Jonathan Laidlaw QC and Mr Tom Little for the Respondent in Dlugosz

Mr JA Butterfield for the Appellant Pickering

Mr PJ Cooper for the Respondent in Pickering

David Bentley and Evans Amoah-Nyamekye (instructed by Birds) for the Appellant MDS

Jonathan Rees QC for the Respondent in MDS

Hearing dates: 24 and 31 October 2012

The President of the Queen's Bench Division:



In each of the trials from which these appeals have been brought, the judge was asked by the Crown to admit expert DNA evidence against the defendant where the evidence was Low Template DNA evidence and the DNA derived from a mixed sample to which at least two or three had contributed. In each case, 19 or 20 of the components of the appellant's DNA had been present in the mixture but the experts were unable to give a random match probability. The judge's decision to admit the evidence was the main issue in each of these appeals.

I The general approach

(a) Mixed profile


This court has considered Low Template DNA in several cases including R v Reed and Reed, R v Garmson [2009] EWCA Crim 2698, [2010] 1 Cr app R 23, R v Broughton [2010] EWCA Crim 549, and R v C [2010] EWCA Crim 2578. In Reed and Reed, this court referred briefly to DNA mixtures at paragraphs 50–51:

"A sample may contain DNA from more than one person. This may be identified by there being more than two alleles at one or more of the loci tested. Where there is DNA from more than one person, it is often the case that one person will have contributed more of the DNA than another. That profile is referred to as the major profile and that person is referred to as the major contributor; the profile of the other or others is referred to as the minor profile and the provider of that profile as the minor contributor.

If there are two contributors and four alleles at a locus, this will be because each of the persons has two different alleles at that locus. However, if the individuals have common alleles at a given locus, then they will overlap each other and not be shown separately. This is referred to as masking."


In Garmson, the appeal against a conviction for rape and sexual assault heard with Reed and Reed, there was a mixed profile, the major contributor being the female victim. The Crown sought to attribute the minor profile to the appellant; there were "foreign" alleles that could not be attributed to either, but the Crown's expert was able to calculate a random match probability, though this was challenged by the appellant at trial and on the evidence heard on the appeal.

(b) No statistics of random match probability available


In the first two appeals it was accepted that it was not possible to determine a random match probability. In the third (as we set out at paragraphs 99–100 below), the judge ruled inadmissible the evidence of Professor Balding, Professor of Statistical Genetics at University College London who had further refined his method of statistical analysis as applied to a mixed profile. In the result therefore, all three appeals proceeded on the basis that the DNA evidence was given without any of the experts being able to provide a random match probability, essentially because it was not possible to attribute particular alleles to any contributor. It was a further feature of each case, as is common in Low Template DNA cases that it was not possible to tell when the DNA was deposited or how it had been deposited (whether by primary, secondary or tertiary transfer) or the origin of the DNA, such as skin or fluid.

(c) No evidence using the sliding scale of expressions


Nor were the experts who gave evidence in the trials of Dlugosz and Pickering from which these appeals originated prepared to give evidence using the sliding scale of expressions used in other areas of expert evidence such as handwriting, fibres, glass fragments, footwear patterns or "facial mapping". As Hughes LJ in giving the judgment of the Court in R v Atkins & Atkins [2009] EWCA Crim 1876, [2010] 1 Cr App R 8 pointed out at paragraphs 22–3, the sliding scale

"does not have a scientific basis, in the sense of an arithmetical or numerical scale. It is simply a means of expressing a conclusion..

But we do not agree that the absence of such a database means that no opinion can be expressed by the witness beyond his rehearsing his examination of the photographs. 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 expert in that case had set out a sliding scale or hierarchy with expressions ranging from "lends no support" to "lends powerful support" (see paragraph 8 of the judgment). The court concluded at paragraph 31 that an expert could express an evaluative opinion

"by use of conventional expressions, arranged in a hierarchy, such as those used by the witness in this case and set out in paragraph 8 above. We think it preferable that the expressions should not be allocated numbers, as they were in the boxes used in the written report in this case, lest that run any small risk of leading the jury to think that they represent an established numerical, that is to say measurable, scale. The expressions ought to remain simply what they are, namely forms of words used. They need to be in an ascending order if they are to mean anything at all, and if a relatively firm opinion is to be contrasted with one which is not so firm. They are, however, expressions of subjective opinion, and this must be made crystal clear to the jury charged with evaluating them."

(d) Evidence as to whether the defendant might or might not be a contributor


There was no dispute in the first and third appeals that DNA evidence from a mixed profile could be used simply to establish that the defendant might have been a contributor or could not have been a contributor. It was accepted that it is often useful for a jury simply to know that fact without any further elaboration. What was in issue was what was necessary for an evaluative opinion to be given so that the jury could assess the significance of the DNA findings.

(e) Is statistical evidence required if an evaluative opinion is to be given?


It was the primary submission of the appellants in each case that unless statistical evidence of match probability could be given, then evaluative evidence should not be admitted. That was because the jury needed to have a firm basis on which they could evaluate the significance of the evidence given. In the absence of statistical evidence it was not possible to do so. The need for that firm basis had been spelt out in R v Doheny; R v Adams [1997] 1 Cr App R 369.


We cannot accept that argument. As is clear from the judgments in Atkins and Atkins (paragraph 23) and T (Footwear Mark Evidence) [2010] EWCA Crim 2439 (at paragraph 92) the fact that there is no reliable statistical basis does not mean that a court cannot admit an evaluative opinion, provided there is some other sufficiently reliable basis for its admission. As is clear from Reed and Reed and R v Weller [2010] EWCA Crim 1085, evaluative opinions were given in relation to the ways in which DNA could be transferred without there being any statistical database. We see no reason for concluding that evaluative evidence as to whether the profile can be attributed to a defendant or other person should be placed in a special category and should necessarily be excluded.

(f) Is a hierarchy of support required if evaluative evidence is to be given?


We therefore turn to consider the alternative submission that in giving an evaluative opinion an expert can only give evidence if he is able to use a hierarchy or sliding scale of support (as for example set out in Atkins and Atkins). It was submitted that if the expert cannot give his evaluative opinion using the hierarchy or sliding scale of support, then the evidence is inadmissible, as it does not have a sufficiently reliable basis.


It is essential to recall the principle which is applicable, namely in determining the issue of admissibility, the court must be satisfied that there is a sufficiently reliable scientific basis for the evidence to be admitted. If there is then the court leaves the opposing views to be tested before the jury: see R v Reed and Reed at paragraphs 111–112.


It was argued that there could not be a sufficiently reliable scientific basis, as the experts could not express an evaluative opinion by reference to the sliding scale or hierarchy. Although it was possible to state that finding all of a defendant's components in a mixed sample was "rare" or "somewhat unusual", this was an informal description and not objective scientific evidence. There was the real possibility that the fact that all of a defendant's components were present in a sample found at a crime scene might lead a jury to conclude that there was a match when plainly there was...

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18 cases
  • Criminal Practice Directions 2015
    • United Kingdom
    • Court of Appeal (Criminal Division)
    • 29 September 2015
    ...matters with which an expert's report must deal, so that the court can conduct an adequate such assessment. 19A.4 In its judgment in R v Dlugosz and Others [2013] EWCA Crim 2, the Court of Appeal observed (at paragraph 11): "It is essential to recall the principle which is applicable, namel......
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    • Court of Appeal (Criminal Division)
    • 29 September 2015
  • Kevin Brecani v R
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    • Court of Appeal (Criminal Division)
    • 19 May 2021
    ...expert's report must deal, so that the court can conduct an adequate such assessment. 19A.4 In its judgment in R v Dlugosz and Others [2013] EWCA Crim 2, the Court of Appeal observed (at paragraph 11): ‘It is essential to recall the principle which is applicable, namely in determining the ......
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    • Court of Appeal (Northern Ireland)
    • 14 December 2023
    ...evidence. [91] We acknowledge that the law permits evidence of the type given by Ms Beck. In R v Dlugosz; R v Pickering; R v S (MD) [2013] 1 Cr App R 32 it was confirmed that evaluative opinion could be admissible regarding DNA evidence, even without a statistical basis. Sir John Thomas P, ......
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14 books & journal articles
  • Explaining and trusting expert evidence: What is a ‘sufficiently reliable scientific basis’?
    • United Kingdom
    • Sage International Journal of Evidence & Proof, The No. 24-3, July 2020
    • 1 July 2020
    ...author:Tony Ward, Northumbria University, City Campus East, Newcastle upon Tyne, UK.E-mail: tony.ward@northumbria.ac.uk1. RvDlugosz [2013] EWCA Crim 2, [2013] 1 Cr App R 32 at [11].The International JournalofEvidence & Proof2020, Vol. 24(3) 233–254ªThe Author(s) 2020Article reuse guidelines......
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    • Sage Journal of Criminal Law, The No. 85-3, June 2021
    • 1 June 2021
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    • Sage International Journal of Evidence & Proof, The No. 20-1, January 2016
    • 1 January 2016
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    • Sage Journal of Criminal Law, The No. 80-5, October 2016
    • 1 October 2016
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