Editing DNA profiling (section)

===England and Wales===
Evidence from an expert who has compared DNA samples must be accompanied by evidence as to the sources of the samples and the procedures for obtaining the DNA profiles.<ref>{{cite court|litigants=R v. Loveridge |reporter=EWCA Crim|opinion=734<!-- this might in fact be 973! -->|year=2001|url=}}</ref> The judge must ensure that the jury must understand the significance of DNA matches and mismatches in the profiles. The judge must also ensure that the jury does not confuse the match probability (the probability that a person that is chosen at random has a matching DNA profile to the sample from the scene) with the probability that a person with matching DNA committed the crime. In 1996 ''R v. Doheny''<ref>{{cite BAILII| litigants = R v. Doheny|court = EWCA| division = Crim| year = 1996| num = 728| parallelcite = [1997] 1 Cr App R 369| date = 31 July 1996| courtname = [[Court of Appeal of England and Wales|Court of Appeal]]| juris =}}</ref>

Juries should weigh up conflicting and corroborative evidence, using their own common sense and not by using mathematical formulae, such as [[Bayes' theorem]], so as to avoid "confusion, misunderstanding and misjudgment".<ref>{{cite BAILII| litigants = R v. Adams| court = EWCA| division = Crim| year = 1997| num = 2474| date = 16 October 1997| courtname = [[Court of Appeal of England and Wales|Court of Appeal]]}}</ref>

====Presentation and evaluation of evidence of partial or incomplete DNA profiles====
In ''R v Bates'',<ref>{{cite BAILII | litigants = R v Bates | link =  | country =  | court = EWCA | division = Crim | year = 2006 | num = 1395 | para =  | eucase =  | parallelcite =  | date = 7 July 2006 | courtname = [[Court of Appeal of England and Wales|Court of Appeal]] | juris = }}</ref> Moore-Bick LJ said:

{{Blockquote|We can see no reason why partial profile DNA evidence should not be admissible provided that the jury are made aware of its inherent limitations and are given a sufficient explanation to enable them to evaluate it. There may be cases where the match probability in relation to all the samples tested is so great that the judge would consider its probative value to be minimal and decide to exclude the evidence in the exercise of his discretion, but this gives rise to no new question of principle and can be left for decision on a case by case basis. However, the fact that there exists in the case of all partial profile evidence the possibility that a "missing" allele might exculpate the accused altogether does not provide sufficient grounds for rejecting such evidence. In many there is a possibility (at least in theory) that evidence that would assist the accused and perhaps even exculpate him altogether exists, but that does not provide grounds for excluding relevant evidence that is available and otherwise admissible, though it does make it important to ensure that the jury are given sufficient information to enable them to evaluate that evidence properly.<ref>{{cite web |url=http://www.wikicrimeline.co.uk/index.php?title=DNA_profiling#Presentation_and_evaluation_of_evidence_of_partial_or_incomplete_DNA_profiles |title=WikiCrimeLine DNA profiling |publisher=Wikicrimeline.co.uk |access-date=2010-04-03 |url-status=dead |archive-url=https://web.archive.org/web/20101022013511/http://www.wikicrimeline.co.uk/index.php?title=DNA_profiling#Presentation_and_evaluation_of_evidence_of_partial_or_incomplete_DNA_profiles |archive-date=2010-10-22 }}</ref>}}